Ryukyu (Oita Sesame-Soy Marinated Sashimi)

Grind the toasted sesame in a mortar for 2 to 3 minutes, until fragrant and oily while a little grain texture remains.

Add the soy sauce, sugar, and sake to the ground sesame in that order.

Whisk thoroughly until almost no sugar grains can be felt, producing a cold marinade.

Keep the sashimi-grade yellowtail at or below 4°C until opening.

With a clean, chilled knife and board, slice across the grain into bite-size sashimi about 7 mm thick.

Place the yellowtail in a chilled nonreactive container, pour the marinade evenly over it, and fold gently.

Cover and marinate in the refrigerator for only 10 minutes, turning once halfway.

Slice the scallions into 2 mm rounds.

Divide the yellowtail among five bowls, spoon over a little marinade to taste, scatter the scallions evenly, and serve immediately chilled or over hot rice.