The one question I get asked at every sushi-making class is: “what is Sushi Grade fish?” It’s as inevitable as heartbreak. And it comes usually in response to my own question: “what are the first two words that come to mind when thinking about sushi?” The answer is, invariably: “fresh” and “raw”. So I tease the students by meandering around the issue and speaking to the total sushi-eating experience in North America. And sushi-eating is full of rot. Literally.
Consider soy sauce. A by-product of the miso-making process, which is as low-tech as it gets when it comes to making rotten food a gastronomic enterprise. You mash cooked soybeans and steamed rice, throw in a bit of salt for seasoning, infest it with koji-kin (an enzyme-producing mold) and let it sit in a warm, dank room for weeks, and out comes miso. The black tar-like liquid oozing out at the end of the process is soy sauce. Sure, full of glutamate, which our body craves, but rot nonetheless. Bonito flakes, just to cite another example, and one of the few key ingredients making up Japan’s ubiquitous seafood broth, dashi, is also a product of the koji-infested rotting process. And it is in everything we associate with eating sushi.
So, here is the truth about “Sushi Grade” fish: there is no such thing. Having said that, there are complexities, which will be discussed in another post. Suffice it to say for now that a truly sushi grade tuna, for instance, would have to be hauled onto a boat, killed, cleaned and gutted, and its flesh carved up immediately for consumption, to be considered Sushi Grade. And good luck to your teeth and gums in your attempt to chomp down on it. You might as well chew on a Goodyear radial tire. In truth, a fish becomes Sushi Grade depending on how long it has been dead. Each species of fish undergoes enzymatic breakdown at a different rate then every other. At Tsukiji market in Tokyo (and there is no less an authority), depending on how long each fish has undergone this process, they stick one of two stickers onto a fish for sale: “For Cooking” or “Sushi Grade”.
Timing is everything with dead fish. Decomposition adds to the flavor of fish just as it does to beef. For the latter, we call this process “aging”. Sushi Grade is determined by aging, too, but unlike beef, the longer you let it decompose, the more likely it will make you very sick. In North America, Sushi Grade is as much a marketing gimmick, allowing fishmongers to reach deeper into your pocket, as it is based on a widespread confusion about what happens from ship to table- from dead to even more dead. Further obfuscating the issue is the type and size of fish, as well as if it is caught in freshwater or saltwater.
“So, Sang, what do I do if I want to serve sushi at home for my friends and family?” For now, purchase only fish the fishmonger- even the $12/hr part-time student standing behind a counter at Metro- knows the origins of. Then, make sure that this jives with what credible organizations like Seafood Watch or Fish2Fork says is cool to eat, that by making fish purchases you will not be doing needless harm to the environment. Forget about the tags of “sushi grade” or “sashimi grade”. It means little at most fish counters. Or, at your own peril (and mine), buy mindlessly. It’s up to you. But if you are going to invite me to your sushi party and you can’t tell me where this “fresh” and “raw” fish is from, best you pass me the apron.
I will work the grill.