Editor’s note: The theme of Gohan Lab is to help people make simple, tasty “gohan” (meals).

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Having successfully thawed a block of tuna as shown last week, learn how to slice it into sashimi to make a simple marinated fresh tuna bowl introduced by the pros from Toyosu Market in Tokyo in the second installment of how to handle frozen tuna.

The chosen part is the lean “akami” that has the aroma, flavor and umami characteristic of tuna and is affordable as well. When the slices are marinated in soy-based sauce, the surface turns smooth to match the vinegar-seasoned rice.

When slicing tuna into sashimi, be careful of the white line-like tendons. To support the muscles of fish that swim long distances at high speed, the tendons are more developed in the heavy head and toward the tail that moves a lot. They are thicker near the skin than the center. The overall flavor will be enhanced if the tendons are cut nicely.

For bowl dishes, the fish should be sliced thinly at an angle. This way, the slices will taste smooth and the coating of the sauce will have a volume-increasing effect to the eye. A key is the angle of the fish placed on the cutting board.

The correct way is to cut using the kitchen knife as if severing the flow of the tendons. Home knives will work if the tuna is chilled sufficiently so the meat has tightened.

Use the entire blade from near the handle to the tip as if pulling smoothly.

The transaction volume of tuna at Toyosu Market is about a hundred and several tens of tons a day. While the market increases its outlets overseas where Japanese cuisine is becoming popular, transmitting information to consumers is another important role of the market to handle the limited resources with care.

Although there are “kuro-maguro” (Pacific bluefin tuna), “minami-maguro” (southern bluefin tuna), “mebachi” (bigeye tuna) and “kihada” (yellowfin tuna), Yutaka Kurihara, vice chairman of Omono Gyokai, said, “The quality of tuna varies depending on what they feed on in which fishing area.”

It is currently winter in the Southern Hemisphere and fatty fresh minami-maguro is arriving at the market.

Although the amount is small, mebachi and kihada caught inshore are also available, and when the season comes, fresh ones will line the auction hall.

"Kihada arrives from Miyazaki and Nichinan in early spring when plums blossom, while mebachi comes from Miyagi and Shiogama around the ‘higan’ (season around the autumnal equinox). Fish that are in season taste exceptional. We want to pass on ways to enjoy them."


(Supervised by Yutaka Kurihara in the cooking aspect and Midori Kasai in the cookery science aspect)

* Ingredients and cooking utensils (Serves two)

1 small block (150 grams) fresh tuna, 1 Tbsp soy sauce, 1 tsp sweet mirin sake, 300 grams cooked rice, 1 1/2 Tbsp vinegar, 1/2 tsp salt, 1 Tbsp sugar, wasabi, kitchen knife and cutting board, flat container, wooden tub to make sushi rice (handai) or bowl, chopsticks for cooking and rice paddle

1. Have a block of tuna ready. If it is pre-thawed, remove from plastic tray, pat the surface dry, wrap in paper towel, cover with plastic wrap or place in plastic bag and cool in fridge.

2. To make sushi rice, mix vinegar, salt and sugar and melt. Place warm rice in rice tub. Pour vinegar mixture in circular motion, mix with rice paddle and fan to cool. Wet dishcloth, wring out water. Cover rice tub with it.

3. Place tuna block on cutting board wiped dry. Adjust position so the knife blade touches against flow of white tendons. If kitchen knife is held with right hand, tendons should flow from top left to bottom right.

4. <“Sogi-giri” (Slicing diagonally)> Start from left end of block. Tilt blade somewhat and cut at an angle by drawing knife from the back toward you. Slices should be 6 to 7 mm thick (PHOTO A). After each cut, line up slice on another area of cutting board.

5. Mix soy sauce and sweet mirin sake in flat container. Lay tuna slices and marinate for 2 to 3 minutes while turning sides halfway (PHOTO B). Serve sushi rice in bowl, drain sauce from tuna and lay on rice (PHOTO C). Serve with wasabi.

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Yutaka Kurihara is the vice chairman of Omono Gyokai, a trade group of intermediate wholesalers specializing in tuna.Midori Kasai is a professor at Ochanomizu University and chairwoman of the Japan Society of Cookery Science.


<Flatly cut medium-fatty tuna (chutoro) >

“Hirazukuri” is a style where the block of fish is sliced at right angles. Starting from the right end of block, the part of the knife near the handle is placed at right angle and pulled toward you. The slices should be about 1 cm thick. If meat sticks to the blade, hold block lightly with opposite hand and pull out knife. Insert chopsticks under sashimi, lift and serve on plate. To make accompanying garnish, cut daikon radish into fine strips, release in water and when it turns crisp, drain. By placing “shiso” leaves between daikon and tuna, the tuna will not color the radish.


Among the proteins found in the muscles of fish and meat, there are ones that melt in salt. By marinating tuna, the salt in the soy sauce causes the surface to melt, turning the slices glazed and smooth. The texture also becomes somewhat sticky in the mouth. This effect is more noticeable with “akami” with higher protein content than fatty “toro.”

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This column, translated from The Asahi Shimbun’s Gohan Lab column, will next appear on Sept. 11.