- Jul 24, 2020

How Do You Prepare Tuna for Sushi?

(Image: Japan Tuna Co-operative association)

For Edo•Mae(Tokyo) Style Sushi Restaurant, Tuna is the signature fish that defines their quality, style and artistry. Sushi chefs consider choosing their tuna one of the most important tasks at the fish market. It's the highlight of the "omakase" or the equivalent of the main dish in French and Italian course meal.

To a sushi chef, a sushi restaurant without Maguro/Tuna is not a sushi restaurant. (Here is my article explaining the story)

Here are the detailed steps in making Tuna sushi (both nigiri and rolls).

1. First, get tuna

When Japanese say tuna for sushi, it usually means, Maguro, tuna with red flesh. There are mainly three kinds of Maguro used for sushi: Yellowfin, Bigeye and Bluefin. In the US (and some in Japan ), Albacore Tuna is also used for sushi, and they are called white tuna.

Now, the first thing is to go purchase tuna.

Here is a diagram showing parts of bluefin tuna.

Red Meat: A, B, C F

Toro (Fatty Tuna Belly): D, E

Price (high to low): D, E, B, A, C&F

A, B, C are all "Red" meat with B being the highest quality, A the second and C being the least. The reason is that C is closest to the tail. The tail meat is the leanest because it gets the most exercise, thus contains the least amount of fat.

D is "O-Toro" (the word "O" means big in Japanese, referring to the amount of fat) or The Fattiest Tuna Belly. Notice the color of the meat is light pink and this is due to the fat content. E is the "Chu-Toro" or Medium Fatty Tuna belly, and F is Red meat.

As for the price, D is the highest, E the second and B, A followed by C and F being equal.

If this wad Big Eye, the chance of E being O-Toro is less and mostly, it will be Chu-Toro because Big Eye is smaller than Blue Fin. Yellowfin is all red meat and rarely has Toro and if so, it's more like "small" toro.

Thought I mentioned earlier that the first step is to go "buy" the tune, it's very unlikely you will see a whole tuna at a retail store in Japan or the US (or anywhere else in the world) simply because it will be too much fish to eat for one household. In fact, most restaurants (in the US) usually get 1/4 tuna already fillet because even for them, getting a whole tuna is too much. (I've worked for one restaurant in LA, who occasionally ordered a whole tuna.) The amount of tuna a restaurant buys depends on the size of tuna, the size of the restaurant and the quality of the restaurant. If it's Blue fin, most of the sushi restaurants in Japan gets the best part - belly with toro.

Here is a block of tuna, close to "D" in the diagram.

2. Cut into blocks called "Saku"

From here, you need to cut into small blocks for sushi. A block of tuna is called “Saku.”

Here is a picture showing you how.

Image Courtesy of Australian Southern Bluefin Tuna Industry Association

3. Cut into thin slices

To cut tuna for nigiri, you need to cut against the grain, usually 30-degree angle or so, and about 1/4" or so thick. The most difficult part of the cutting is to determine how thick/thin to cut, as this will dramatically affect how your nigiri taste. In general, tuna tastes good when cut thick. When thin, it will lose the tuna flavor. You can experiment this by trying two different cuts: paper-thin cut and thick-cut tuna to see how they taste different. When slicing tuna, pull your knife backward instead of push forward, as you'd normally do to cut vegetables and meats.