This Japanese specialty requires very fresh fish.
- 1 1⁄2 cups short-grain Japanese rice
- 1 1⁄2" pieces konbu (dried sea kelp)
- 2 tbsp. sugar
- 1 tsp. salt
- 2 tbsp. rice vinegar
- 10 oz. very fresh yellowfin or bigeye tuna, chopped
- 1 scallion, trimmed and finely chopped
- 4 tsp. sriracha chile sauce
- 4 tsp. Asian chili oil
- 2 tbsp. masago (smelt roe)
- 4 sheets yaki-nori (toasted seaweed), halved crosswise
Put rice into a medium pot, cover with water, and swish around with your hand until water clouds. Drain; repeat process 3–4 more times, until water remains clear. Drain again, return rice to pot, add sea kelp and 1¾ cups water, and bring to a boil over medium-high heat. Boil until liquid barely covers rice, 8–10 minutes; cover, reduce heat to medium-low, and steam until rice is tender, 15–20 minutes more; discard sea kelp.
Transfer rice to a large bowl. Allow to cool briefly. Dissolve sugar and salt in vinegar in a small bowl, add to rice, and gently stir with a wooden spoon until rice is just warm.
Combine tuna, scallions, chile sauce, oil, and roe in a bowl and set aside. Position 1 sheet of seaweed, shiny side down, with long edge parallel to edge of work surface. Spread ¼ cup of the rice onto left third of seaweed. Spread 2-3 tbsp. of the tuna mixture over rice. Beginning with the left side, roll seaweed around rice and tuna on the diagonal. Repeat process with the remaining seaweed, rice and tuna.