The Story of Sushi

by Trevor Corson

  Yellowtail scales aren’t as tiny as mackerel scales, and for a chef, that means they are inconvenient—too big to eat, too small to scrape off. Zoran used his willow-leaf knife to saw lightly across the surface of the fish, as if he were skinning a big mango. The outer skin and scales came off in strips.

  “Okay, let me show you the other fish.” He led the students into the kitchen. He set a pair of oversized polyethylene cutting boards on the kitchen table, then disappeared into the walk-in.

  When Zoran reemerged, he had a whole fish in his arms. The thing was three feet long. It still had everything, including its head. Zoran dumped it on one of the cutting boards with a thud and returned for a second one just like it. The tail fins on these fish were distinctly yellow.

  “These are cheap,” Zoran said. “Two dollars a pound—and you get what you pay for.” He waved his hand in front of his nose. “Wow, they stink!”

  Takumi laughed, and nodded.

  “You can’t do anything,” Zoran said, “until the scales are off. Good luck!”

  Good luck? That was it? Kate stared at the enormous fish, and made the mistake of breathing through her nose. One of Kate’s classmates started sawing sideways, cutting off scales. The surface of the fish was curved so steeply that he could slice only one narrow section off at a time.

  He stepped aside to let Kate try. She used her willow-leaf blade, but she had trouble getting it to go where she wanted it. The knife had dulled since yesterday. She pushed too hard and cut into flesh. She recoiled and stepped away, leaving a gash. Skinning such a big creature seemed more like skinning a person than a fish. Her classmate kept sawing. It took fifteen minutes just to complete one side. Kate watched.

  “What are scales for?” she asked.

  It was a good question.

  Hundreds of millions of years ago, ocean worms burrowed in the mud for safety, but when they evolved toward fishdom they began to swim out in the open. They developed body armor for protection. The earliest fishes were called placoderms, from the Greek for “plate skin,” and they had big bony plates on their heads and necks.

  The problem with armor plating is that it’s cumbersome. Scales evolved as a less protective but more liberating compromise. What the fish lost in safety they gained several times over in speed and agility. Scales are so useful that they appear all over in nature. The bodies of snakes are covered in scales. Sharks evolved their own version of scales separately from fish. So did insects, for use on their wings.

  Some fish have unusual scales, or none at all, or they lose or gain scales depending on their life stage. These fish are generally off-limits to kosher eaters. According to the Torah, for example, eels are not kosher. Some rabbis consider swordfish not to be kosher because they lose their scales at a young age, in order to swim as fast as possible.

  Zoran watched the students slicing scales off the yellowtail with their hand-forged blades. It was laborious work.

  “Can you believe it’s 2005,” Zoran said, “and we’re still using this technology?”

  He walked to the sink and came back with a steel scouring pad.

  “This isn’t the Japanese way,” Zoran said, “but you can actually use this. Most restaurants that sell a lot of hamachi, they don’t have time, so they use this.” He looked at the pad in his hands. “It works.” Then he put it away. Zoran’s students did things the Japanese way.

  Zoran surveyed the room and put his hands on his hips. “Oooh, I am not looking forward to taking the guts out. It’s going to smell.” He turned to Kate. “Come on, Kate, I haven’t seen you doing any.”

  Kate moved tentatively toward the big yellowtail. She sawed across the surface again. She progressed 2 inches with her dull knife, then cut too deeply again and exposed flesh. She glanced up but Zoran had left the room. One of her classmates stepped in to bring the scaling line back to the surface. She tried again. This time she progressed 4 inches and stopped. She turned to the student next to her.

  “Your turn,” she said.

  Other students weren’t faring much better on the other fish. It looked like a burn victim.

  Zoran reappeared with a Magic Marker.

  “Look out, fish. Tattoo time!” He drew a dotted line behind the head, indicating the best path for decapitating the beast. He stepped out of the way. Kate’s classmate sawed down into the neck along the line, opening a deep gash. He turned to Kate. “Want to take a peek? Put your hand inside?”

  In spite of herself, Kate peered into the gash. Her hand flew to her mouth. She pulled away. Her classmate kept sawing, making crunching sounds. Kate shook her head.

  “It’s the cracking into the bones that gets me,” she said.

  He couldn’t get the knife all the way through the thick spine. He gave up and cut along the belly. Bloated organs popped out like salamis. A sack of eggs slid into view, encased in a net of purple veins. The stench was overpowering.

  Kate grabbed her nose. “Dis-gust-ing!”

  Zoran laughed.

  Kate’s classmate ran his fingers delicately along the guts, trying to determine the best way to remove them. Zoran butted in and simply ripped the organs out in handfuls and dumped them in the trash, spattering blood and globs of tissue all over the cutting board.

  Now it was time to fillet. A large tubular fish like a yellowtail requires a more complex fillet plan than the “three-piece breakdown.”

  With a fillet knife, Zoran traced long incisions around the edges of the fish, then deepened the cuts. He removed an entire side of the fish. Then, he divided it lengthwise with two new incisions on either side of the pin bones.

  Zoran had produced two long blocks of flesh, roughly triangular in cross section and tapered at the tail end. Each long block contained about a quarter of the fish’s muscle mass. A busy sushi bar might go through one or two of these blocks a day.

  This fillet plan was called go-mai oroshi, or the “five-piece breakdown.” It produced four quarters of meat, plus the carcass. The students tried their hand at filleting the other side, and then the other fish. When they had finished, Zoran grabbed one of the carcasses and dangled it over the trash can by its tail.

  “Look at all the meat you’re throwing away,” he said. If the students had been working for a restaurant, these fillet cuts would probably have gotten them fired. Zoran released his grip, and the carcass dropped into the garbage.

  Everything the students had just been through happens every few days in any sushi restaurant that cuts its own fish—except at about quadruple the speed and with a lot more fish. In the kitchen behind any sushi bar, the carnage is fast and furious.

  In the old days, sushi chefs wrapped their fillets of fish in kelp. Now sushi chefs enclose blocks of neta tightly in plastic wrap so they don’t dry out in the refrigerator. At Hama Hermosa, the chefs went through a mile and a half of plastic wrap every month.

  Kate laid paper towels in a neta tray. Zoran loaded the tray with the slabs of meat. He pointed to different shadings of flesh in each piece. Most of the meat was pale, fast-twitch muscle. But the edges of some pieces were dark purple—a sure sign of the presence of iron, and the machinery for employing oxygen for endurance swimming. Together, these sections of dark flesh had composed the narrow strip of slow-twitch muscle that had stretched down each side of the fish, under the skin.

  “Americans don’t like this meat,” Zoran said. “If it’s fresh, Japanese customers will eat it, no problem.”

  The paler, fast-twitch flesh, meanwhile, contained curving, slanted sections of muscle.

  While slow-twitch fibers run parallel to the fish’s body, fast-twitch fibers of fish nest against each other in geometrically complex sheets that angle off the fish’s midline by as much as 45 degrees, forming a series of spiral tracks down the body. The geometry is perfectly calibrated so that all the fibers at a particular point along the length of the fish contract together, regardless of their distance from the backbone. This allows for the maximum exertion of force.

  Zoran
straightened up. “Isn’t this fun?” he asked, smiling.

  After a morning of bloody violence, the students descended into meditative silence and practiced sashimi with the butchered yellowtail. They remembered not to eat it because it wasn’t fresh. One customer had no such compunction. A housefly buzzed around the table and landed on the sashimi, sampling it with apparent relish.

  Kate was trying without success to slice a piece of fiber from her yellowtail using her willow-leaf blade. Zoran materialized next to her. He held out a cheap, mass-produced knife.

  “Try this,” Zoran said.

  Zoran leaned on the table and glared while Kate tried the cheap knife. It cut right through the fiber.

  “Your knife isn’t sharp,” Zoran said. After three days of heavy use, Kate’s high-carbon blade had lost its edge.

  “Today, I want you to stay after class,” Zoran said. “Don’t go home. I want to see how you’re sharpening your knife.”

  “You saw it before,” Kate said.

  “Well,” Zoran said, “you’re obviously not doing something right.”

  Suddenly Kate winced and dropped the knife. She squeezed her left hand into a fist, pressing her thumb against her index finger. She’d finally cut her finger. Bright red blood oozed out. She rushed to fetch a Band-Aid. Zoran stopped her.

  “Don’t leave your fish lying out, Katie.”

  She hesitated.

  “You’re not dying,” Zoran said. “I can see that. You haven’t cut a major artery, have you?”

  She shook her head.

  “Okay, so put your fish away first. Never leave fish lying out.”

  When Kate returned, nursing her cut finger, Zoran addressed the class.

  “Honestly, you guys, today your knives are the sharpest I’ve ever seen in any class, ever. Very good job.”

  He paused.

  “Except Katie. Everybody has to help Katie sharpen her knives today. Don’t let her go home until she’s sharpened her knives. We have to help her along.”

  And with that, Kate was no longer one of the guys. Once more, she’d become the flaky girl who couldn’t do anything right. Moments later, when no one was paying attention, she shut her knife case and slipped out of the building.

  33

  FLATFISH

  With a few simple words, Zoran had dragged Kate all the way back to the first week of school. It was as if she had not gotten past day two, when Zoran yelled in front of the whole class, ‘Kate, your knives are terrible!’ The worst part of it was, it was her own fault.

  She arrived at school early the next morning and helped wash and cook rice. She moved briskly around the cypress tub, mixing vinegar into the rice, while Zoran introduced the day’s lesson.

  “Today we’re doing hirame and karei,” Zoran said. “What’s the difference?”

  One of the students hazarded a guess. “Ugliness?”

  “Well, maybe!” Zoran unwrapped two fish. They looked as if they’d been run over by steamrollers.

  Hirame and karei are Japanese names for the fish that Americans call flounder, halibut, turbot, sole, or plaice, depending on the region and species. Regardless of the names, the main thing about them is that they are all flat—flat as pancakes. And really weird-looking. Both of their eyes are on the same side of their head, and their mouths open sideways, like in a Picasso painting.

  Zoran pointed at the two fish. One was large and one was small.

  “You might say size. But there’s another difference.”

  The students were stumped.

  “See this?” he said. “The small one faces right. The big one faces left.”

  Because flatfish are so flat and strange, most people don’t notice the obvious characteristic that separates the 550 or so species of flatfish into two distinct camps. They point in opposite directions. And just to confuse things, there is at least one species of flatfish, called the starry flounder, that goes both ways. Off the coast of California, half of all starry flounders face right. Off the coast of Japan, all starry flounders face left.

  The Japanese refer to most left-sided flatfish as hirame and most right-sided ones as karei. The best way to tell them apart is by the price tag. At sushi bars in Japan, hirame have a reputation for being more delicious. Most karei are cheaper, and the Japanese eat them cooked more often than raw.

  Flatfish as a group haven’t left behind much of a fossil record. But in a sense, they didn’t need to. Flatfish are themselves striking evidence of the process of evolution. They reveal evolution at its best—and at its worst.

  For fish that want to eat an unsuspecting sea bug or worm for lunch, lying sideways on the sand makes sense. That way, the fish look less like predators and more like rocks. Over time, as the fish lay on their sides imitating rocks, the flatter fish were more successful. Soon they became so flat they simply disappeared into the sand.

  Flatfish also evolved in such a way that both eyes ended up on one side of the fish’s body. Picasso may have considered this beautiful, but generally it’s not the sort of development that counts as an improvement. Imagine a child trying to get through grade school with both eyes on the same side of his nose.

  Yet without such seemingly bizarre mutations, the myriad creatures of the planet—including us—would never have evolved at all. While mutations often cause problems, some are fortuitous, and over time the useful ones add up. Having both eyes on one side of the head could be considered an aesthetic disaster for some, but for a fish that hunts by lying on its side and ambushing passing prey, it’s a vast improvement. It’s much easier to catch things when you have depth perception.

  In a sense, every flatfish today still passes through the entire multi-million-year process of evolution, but compressed into about a week. Flatfish are born perfectly normal. For their first month, a baby flatfish swims around looking like a regular fish. It must come as a rude shock when, over the course of just a few days, its cranium, brain, jaw, nose, and eye sockets all suddenly rotate over to one side.

  Scientists aren’t certain what genes cause the change, but they do know what triggers it. The young fish’s thyroid gland releases a sudden surge of hormones. One side of the fish seems to respond more slowly to the hormones than the other. When researchers suppressed the hormones, the fish never went flat. It remained upright and grew into a more or less regular fish.

  In the case of the starry flounder, where some individuals lean left and some right, the left-sided ones are the oddballs. In all vertebrates, optic nerves carry information from the right eye to the left side of the brain, and from the left eye to the right side of the brain. In left-sided starry flounders, these optic nerves wrap around each other twice.

  While the starry flounder may lean left or right, a species of southern flounder can lean male or female. Which way they swing depends partly on the temperature of the water. Heat generates males. Where cooler waters prevail, the embryos tend to swing female.

  For the Japanese, hirame are such high-class fish that sushi vendors on the streets of old Tokyo rarely sold them. Throughout much of the twentieth century, hirame have, like tai, enjoyed pride of place at fine sushi bars in Japan.

  This may seem surprising because flatfish have less flavor than most other fish. They don’t get much exercise. They spend most of their time lying around impersonating sand. But sushi connoisseurs appreciate flatfish for several reasons. One is the subtlety of their taste. While most flatfish muscle lacks a high concentration of flavor elements, it does contain a variety of interesting amino acids.

  Another attraction is texture. Flatfish muscle contains a high proportion of a connective protein called elastin. The result is what Japanese diners call kori-kori. The term suggests a combination of crunchiness, elasticity, and firmness. Another example of food that is kori-kori is lightly cooked broccoli or asparagus.

  Many Japanese enjoy the sensation of kori-kori and the gradual release of delicate tastes that come from raw flatfish. Flatfish sushi or sashimi rewards slow, thorough che
wing. Some experts recommend that people eat flatfish sushi with their eyes closed, in order to fully appreciate the texture and the subtle interplay of flavors.

  Flatfish have an additional attraction, and the Japanese consider it one of the best features in all of sushi.

  Americans who think fatty tuna belly is the pinnacle of Japanese sushi are mistaken. Zoran pointed to the outermost edge of the larger flatfish’s body.

  “Engawa,” he said. “The adductor muscle is a delicacy. Japanese customers will eat this before they eat toro.”

  Many kinds of flatfish swim without using their main body muscles. In fact, they hardly bend their spines at all. Instead, they have evolved continuous fins running down each edge of their flattened bodies, plus a row of special muscles along the base of each fin. These fin adductor muscles undulate, propelling the fish forward. The fish floats across the sand like a hovercraft.

  The word engawa is an architectural term. It refers to the veranda-like walkways that run around the outside of a traditional Japanese home. Early Japanese fishermen apparently saw a resemblance in the edge fins that run around the outside of flatfish. The engawa muscles contain more elastin, so they’re even chewier, but they also have more flavor, since they get more exercise. In addition, they’re rich with fat. The main body of a flatfish is 1 to 2 percent fat. The engawa is 15 to 20 percent fat.

  In the United States, most people have never heard of engawa. Some fish purveyors know enough to set it aside. It’s sometimes referred to in English as “dorsal fin muscle.” Actually, since a flatfish is a regular fish lying on its side, half of all engawa is technically “anal fin muscle.” But that’s not something sushi chefs emphasize.

  “The karei is local,” Zoran said, “so we’re not going to eat it. We’ll eat the hirame raw.” Again, the local fish wasn’t as fresh as the one that had ridden several thousand miles in a jet.