Step 1

Combine the white and black sesame seeds on a plate and spread them in a thin layer.

Step 2

Whisk the sesame oil and soy sauce together in a small bowl. Using a spoon, drizzle a little of the mixture over each tuna steak and rub with the back of a spoon to cover the entire surface.

Step 3

Season with a little black pepper, then turn the steaks and repeat the process.

Step 4

Dredge the tuna steaks in sesame seeds (sides included), pressing gently to ensure they cover the fish evenly and completely.

Step 5

Film the bottom of a heavy pan with a small amount of vegetable oil, then heat over medium-high heat until shimmering.

Step 6

Working in batches to avoid overcrowding the pan, add 2 of the tuna steaks and sear just long enough for the white sesame seeds to develop a little golden color, 1 to 1-1/2 minutes per side.

Step 7

If desired, you can use tongs to gently support the steaks and sear the edges of the steaks all the way around as well, 15 to 20 seconds total should be enough time.

Step 8

Transfer the tuna to a cutting board and repeat the process with the remaining steaks.

Step 9

Cut the tuna steaks into thin slices and arrange over fresh greens.

Step 10

Serve with soy sauce and wasabi for dipping, steamed rice on the side, and a garnish of sliced scallions.