Step 1

Marinade: In a bowl, whisk together the first 7 ingredients to make a marinade. Towel dry tuna steaks and place in a glass or ceramic dish. Pour marinade over the fish, turning to coat well throughout. Cover tightly and chill several hours to overnight; turn fish over at least once in the middle of marinade time.

Step 2

Sear: Heat 3 TB oil in a large heavy skillet (aluminum or stainless steel; not nonstick) until oil is smoking. Sear ahi steaks 1 1/2 minutes per side on high heat, taking care to flip carefully with a flat, steel spatula. (If your tuna is less than 1 1/2 inches thick, sear for only 1 minute per side.)

Step 3

Rest/Cool: Transfer seared ahi to a large cutting board and let rest/cool 10 minutes. Use a very sharp (serrated works well) knife to slice thinly across the grain.

Step 4

Serve: Serve chilled or at room temp, over your favorite salad greens or crispy Asian salad. Sprinkle with sesame seeds and cilantro or green onions, if desired. Drizzle with Sriracha mayo if desired.