Salt, Fat, Acid, Heat

by Samin Nosrat

  Before you bake a birthday cake for your sweetie pie, do a little reconnaissance. Is it the moist, tender crumb of an oil cake she prefers, or the dense, velvety one of a butter cake? Since even I won’t recommend improvising when you bake, let this information guide you to a recipe using the right fat to make your honey happy.

  With what you know about fat and what you know about salt, you’ll find that you’re closer to riffing than you might think. Fat has a remarkable capacity to affect texture, while salt and fat can both enhance flavor. Practice using salt and fat to improve flavor and texture every single time you cook. If you intend to finish a salad with a shower of creamy ricotta salata, hold back on some of the salt until after you taste a bite of it with its salty garnish. Similarly, when you’re dicing pancetta to add richness to Pasta all’Amatriciana, wait to season the sauce until after it’s absorbed all the salt from the pork. And if a recipe for pizza dough instructs you to add salt after kneading in olive oil, think twice about following it word for word. Start to use what you know to be true to guide you through the vast forests of myth and misinformation that poorly written recipes comprise.

  Improvising begins with notes, and now you have two with which to compose a Salt-Fat melody. Master a third note, and you’ll experience the transcendent harmony of Salt, Fat, and Acid.

  In contrast to the revelations I experienced with Salt and Fat, I’ve learned the value of Acid gradually. It started at home, with the food my mom, grandmothers, and aunts cooked each night.

  Maman, who’d grown up eating lemons and limes as an afternoon snack, never thought a dish tasted right unless it made her pucker. She always added a sour element to the plate, to balance the sweet, the salty, the starchy, the rich. Sometimes it was a sprinkle of dried sumac berries over kebabs and rice. With Kuku Sabzi, a frittata packed with herbs and greens, it was a few spoonfuls of my grandmother Parivash’s torshi, or mixed pickles. For No-Ruz, the Persian New Year, my dad would drive down to Mexico to find sour oranges for us to squeeze ceremoniously over fried fish and herbed rice. Into other classic dishes, Maman layered ghooreh, sour green grapes, and zereshk, the tiny tart fruits known as barberries. But mostly we used yogurt to achieve that desired tang, spooning it over everything from eggs to soups to stews and rice and, though I wince to think of it now, spaghetti with meat sauce.

  I wasn’t like the other kids at school. Looking at my classmates’ peanut butter sandwiches next to the kuku sabzi, cucumbers, and feta Maman packed in my lunch box, it was clear that my home life was dramatically different from theirs. I grew up in a house filled with the language, customs, and food of another place and time. Each year, I eagerly anticipated my grandmother Parvin’s visits from Iran. I loved nothing more than watching her unpack while the room flooded with exotic aromas: saffron, cardamom, and rosewater mingled with the humid, slightly moldy Caspian air that had tucked itself into the fabric lining of her bags over the years. One by one, she’d pull out treats: pistachios roasted with saffron and lime juice, sour cherry preserves, sheets of homemade lavashak, plum leather so sour it made my cheeks hurt. Growing up, I learned from my family to delight in sour foods and let my palate become the most Persian part of me. But it wasn’t until I left home that I realized that there’s so much more to acid than just the pucker.

  As part of my parents’ ongoing efforts to delay our assimilation for as long as possible, we never celebrated Thanksgiving. I first celebrated the holiday in college, with a friend and her family. I loved the hubbub involved in preparing and gathering for the meal, but the actual eating part of Thanksgiving was kind of a letdown. We sat down to a table piled high with food: a humongous whole turkey, roasted and ceremoniously carved; brown gravy made with the drippings; mashed potatoes thick with butter and cream; creamed spinach spiced with nutmeg; Brussels sprouts boiled so long that my friend’s nearly toothless grandmother could easily chew them; and stuffing packed with sausage, bacon, and chestnuts. I really love to eat, but these soft, rich, bland foods bored my palate after just a few bites. Spooning more cranberry sauce onto my plate each time the bowl passed my way, I kept eating in hope of tasting something satisfying. But it never happened, and every year on the fourth Thursday of November I ate until I felt mildly ill, like everyone else.

  Once I started cooking at Chez Panisse, I began to spend the holiday with friends from the restaurant. At my first Thanksgiving with other cooks, my palate never became bored. I never felt like eating was a chore. I never felt sick afterward. This certainly wasn’t because the foods we’d cooked were somehow healthier or more virtuous. So what was it?

  It hit me that the Thanksgiving dinners I’d spent with other cooks mirrored the traditional Persian meals I’d grown up eating. Acid had been tucked into every dish, and it had brought the meal to life. Sour cream lent a tang to mashed potatoes. A splash of white wine added just before serving lightened the gravy. Hidden in the big, beautiful mass of stuffing among torn sourdough croutons, greens, and bites of sausage were prunes soaked in white wine—secret caches of acid, most welcome. Roasted winter squash and Brussels sprouts were tossed in an Italian Agrodolce, a sauce made with sugar, chilies, and vinegar. The salsa verde featured fried sage, a welcome partner to the cranberry-quince sauce that I’d made with a nod to the Persian quince preserves Maman jarred every autumn. Even dessert, with a drizzle of dark caramel for the pies and a touch of crème fraîche folded into the whipped cream, had a tang. It dawned on me that the reason why everyone spoons so much cranberry sauce over everything at Thanksgiving is that on most tables, it’s just about the only form of acid available.

  I began to see that the true value of acid is not its pucker, but rather, balance.

  Acid grants the palate relief, and makes food more appealing by offering contrast.

  Soon after, I learned another of acid’s secrets. Late one morning at Chez Panisse, I was rushing to finish a batch of carrot soup in time for lunch. Like most of the soups we served in the café, it was pretty simple. I sweated onions in olive oil and butter. I peeled and sliced the carrots and added them to the pot once the onions were soft. I submerged the vegetables in stock, seasoned with salt, and simmered the soup until everything was tender. Then I blended the contents of the pot into a velvety purée and adjusted the salt. It tasted perfect. I brought a spoonful to Russ, the eternally boyish chef, as he rushed upstairs for the menu meeting with the servers. He tasted it, and without pausing to turn around, said, “Add a capful of vinegar to the pot before you bring it up!”

  Vinegar? Who’d ever heard of putting vinegar in soup? Was Russ crazy? Did I hear him right? I didn’t want to ruin the entire pot, so I took a spoonful of my beautiful soup and added a single drop of red wine vinegar. Tasting it, I was floored. I’d expected the vinegar to turn the soup into a sweet-and-sour abomination. Instead, the vinegar acted like a prism, revealing the soup’s nuanced flavors—I could taste the butter and oil, the onions and stock, even the sugar and minerals within the carrots. If blindfolded and quizzed, never in a million years would I have been able to identify vinegar as one of the ingredients. But now, if something I cooked and seasoned ever tasted so dull again, I’d know exactly what was missing.

  Just as I’d learned to constantly evaluate a dish for salt, now I knew I needed to always taste for acid, too. It was finally clear to me—acid is salt’s alter ego. While salt enhances flavors, acid balances them. By acting as a foil to salt, fat, sugar, and starch, acid makes itself indispensable to everything we cook.

  WHAT IS ACID?

  Technically, any substance that registers below 7 on the pH scale is an acid. I don’t have a working pH meter in my kitchen—I broke mine while testing everything in my kitchen for the chart—and I’m guessing you don’t, either. No matter. We’ve all got a much handier acid sensor—a tongue. Anything that tastes sour is a source of acid. In cooking, acid usually comes in the form of lemon juice, vinegar, or wine. But, like fat, acid has myriad sources. Anything fermented, from cheese and sourdough bread to
coffee and chocolate, will lend a pleasant tang to your food, as will most fruits, including that vegetable-posing chameleon, the tomato.

  ACID AND FLAVOR

  Acid’s Effect on Flavor

  The term mouthwatering has long been a synonym for delicious. Foods that are the most enjoyable to eat cause our mouths to water—that is, to produce saliva. Of the five basic tastes, acid makes our mouths water the most. When we eat anything sour, our mouths flood with saliva to balance out the acidity, as it’s dangerous for our teeth. The more acidic the food, the more saliva rushes in. Acid, then, is an integral part of many of our most pleasurable eating experiences.

  Yet on its own, acid isn’t particularly gratifying. It’s the way acid contrasts with other tastes that heightens our pleasure in foods. Like salt, acid heightens other flavors. But it works a bit differently: while the salt threshold is absolute, acid balance is relative.

  Think of seasoning a simple pot of broth with salt. When the salt concentration passes a certain point, the broth will become inedible. The only way to salvage the broth is to add more unseasoned liquid to reduce the salt concentration, increasing the total volume considerably.

  Acid balance is different. Think of making lemonade. Measure out the lemon juice, water, and sugar, but mix together only the lemon juice and water. Take a sip, and it will taste unpalatably sour. Then add the sugar, and taste again. It’ll be delicious. Yet the lemonade is no less acidic: the pH, or measure of acidity, remains constant after the sugar is added. The acidity is simply balanced by sweetness. And sugar isn’t acid’s only counterpoint: salt, fat, bitterness, and starch also invariably benefit from the welcome contrast of acid.

  The Flavor of Acid

  Pure acid tastes sour—nothing less, nothing more. Sourness isn’t necessarily pleasant or unpleasant. Taste a drop of distilled white vinegar—the stuff we all keep around for household tasks like unclogging drains and cleaning the stove. You’ll see it’s more or less flavorless. It just tastes sour.

  Many of the delicious flavors we associate with acidic ingredients—for example, the distinctive, fruity tang of a wine or the funkiness of a cheese—result from how these ingredients are produced. Everything from the type of wine used to make a vinegar or the kind of milk or bacteria used to make a cheese will affect the flavors of these acidic ingredients. Even the same cheese, aged for different lengths of time, will taste more acidic and complex in flavor, which is why we call a young cheddar mild and an aged one sharp.

  Acids from different sources vary not only in flavor but also in concentration. All vinegars are not equally acidic. Nor is the acidity of citrus juice consistent. In John McPhee’s 1966 book Oranges, the literary journalist illustrates how natural elements affect flavor. First, he explains how the acidity of oranges diminishes with an orchard’s increasing proximity to the equator. One particular Brazilian variety is practically acid-free! He goes on to describe in characteristic detail how not only the location of a tree but the location of an orange on a tree, will affect flavor.

  Ground fruit—the orange that one can reach and pick from the ground—is not as sweet as fruit that grows high on the tree. Outside fruit is sweeter than inside fruit. Oranges grown on the south side of a tree are sweeter than oranges grown on the east or west sides, and oranges grown on the north side are the least sweet of the lot . . . Beyond this, there are differentiations of quality inside a single orange. Individual segments vary from one another in their content of acid and sugar. . . . When [orange pickers] eat an orange . . . they eat the [sweeter] blossom half and throw the rest of the orange away.

  These kinds of natural variations mean you can’t know whether your orange is as acidic, ripe, or sweet as the one the recipe tester used in some distant kitchen. I once spent an entire summer making and canning sauce with Early Girl tomatoes from a friend’s farm. Every single batch I made was different from the last—some tomatoes were watery, others were more flavorful. Some were sweet, others were more acidic. Any recipe I might have written for the sauce the first week of the summer would have been completely inaccurate by the last week. And these were all the same variety of tomatoes from the same farm! This is another reason why you can’t always rely solely on recipes in the kitchen. Instead, taste as you go, develop a sense for acid balance, and trust your instincts.

  Acids of the World

  Many iconic dishes are defined by their particular acids: a peanut butter sandwich, for example, suffers without the tang jelly provides. No proper Brit would consider eating a plate of fish and chips without malt vinegar. Imagine carnitas tacos without a spoonful of salsa. Or xiao long bao, the classic soup dumplings of Shanghai, served with anything other than Chinese black vinegar. Just as with cooking fats, acid can change the direction of a dish, so let geography and tradition guide your choice of which one to use.

  Vinegars

  In general, a region’s vinegar reflects its agriculture. Italy, France, Germany, and Spain—countries known for wine production—make good use of wine vinegars in their cooking. Choose sherry vinegar for Romesco, the Catalonian sauce made with peppers and toasted nuts, champagne vinegar for mignonette sauce to serve with oysters, and red wine vinegar to dress radicchio and to make blaukraut, the classic German braised red cabbage. On the other hand, rice vinegar is a staple in many Asian countries—from Thailand and Vietnam to Japan and China. Brits and Germans turn to apple cider vinegar to dress salads, as do cooks in the American South. Southerners also have an affinity for cane vinegar, which is also the acid of choice in the Philippines, where sugarcane is a major crop.

  Citrus

  When it comes to citrus, lemon trees are well suited to the coastal climates in Mediterranean countries, so choose lemon to squeeze into tabbouleh and hummus, and over grilled octopus, Niçoise salad, or Sicilian fennel and orange salad. Lime trees, on the other hand, grow more readily in tropical climates, so limes are the preferred citrus everywhere from Mexico and Cuba to India, Vietnam, and Thailand. Use limes in guacamole, pho ga, green papaya salad, and kachumbar, the Indian answer to pico de gallo. One form of citrus you should never use, though, is bottled citrus juice. Made from concentrate and doctored with preservatives and citrus oils, it tastes bitter and doesn’t offer any of the clean, bright flavor of fresh-squeezed juice.

  Pickles

  From Indian achar to Iranian torshi, from Korean kimchee to Japanese tsukemono, from German sauerkraut to chow-chow in the American South, every culture has its pickles. A few slices of steak can easily become a bowl of Korean bibimbap if piled high with kimchee, or they can become a taco with a few pickled carrots and jalapeños depending on what’s in the fridge.

  Dairy

  Let cultured dairy products be the secret weapon in your quest for acid balance. Change a salad by topping it with cheese, be it Greek feta, Italian gorgonzola, or Spanish Manchego. Spoon sour cream over latkes, Mexican crema over tacos, crème fraîche onto a French berry tart, and yogurt over the little lamb kebabs most of Eastern Asia calls Kufte.

  Look at a lamb shoulder and know you can take it to Morocco by braising it with preserved lemons, to the south of France with some white wine and Picholine olives, or to Greece with red wine and tomatoes. The same cabbage slaw can evoke the American South when made with mustard and cider vinegar, Mexico when made with lime juice and cilantro, or the Chinese kitchen when spiked with rice wine vinegar, scallions, and toasted peanuts. Learn to not only consider, but also take advantage of, the flavor of an acid to guide the direction a dish takes.

  HOW ACID WORKS

  Though acid primarily affects flavor, it also can trigger chemical reactions that change the color and texture of food. Learn to anticipate these effects so you can make better decisions about how, and when, to add acid.

  Acid and Color

  Acid dulls vibrant greens, so wait until the last possible moment to dress salads, mix vinegar into herb salsas, and squeeze lemon over cooked green vegetables such as spinach.

  On the other hand, acid
keeps reds and purples vivid. Cabbage, red chard stems, or beets will best retain their color when cooked with anything slightly acidic, such as apples, lemon, or vinegar.

  Raw fruits and vegetables that are susceptible to oxidation, the enzymatic browning that results from exposure to oxygen—sliced apples, artichokes, bananas, and avocados—will retain their natural color if coated with a little acid or kept in water mixed with a few drops of lemon juice or vinegar until they are ready to cook or eat.

  Acid and Texture

  Acid keeps vegetables and legumes tougher, longer. Anything containing cellulose or pectin, including legumes, fruits, and vegetables, will cook much more slowly in the presence of acid. While ten to fifteen minutes of simmering in water is enough to soften carrots into baby food, they’ll still be somewhat firm after an hour of stewing in red wine. The acid in tomatoes explains why those pesky onions float to the top of a pot of sauce or soup and stay there, never getting soft, even after hours of cooking. To prevent this crunchy mishap, cook onions until they’re tender before adding any tomatoes, wine, or vinegar to the pot.

  When cooking beans or any legumes, including the chickpeas for hummus, a pinch of baking soda will gently nudge the bean water away from acidity toward alkalinity, ensuring tenderness. And, just like those onions, cook legumes until they are completely tender before adding anything acidic. A great Mexican chef once told me that dousing cooked beans with vinegar or vinaigrette sort of “uncooks” them, tightening and toughening the skins a bit. Account for that tightening when preparing beans for a salad, and cook the beans just a touch longer than you might otherwise.