On a plate, toss together your white and black sesame seeds. Roll your ahi tuna in the sesame seed mixture on all sides.

Heat a pan on medium-high heat with a drizzle of toasted sesame oil. Place your sesame ahi in the skillet, and sear for about 15 to 20 seconds on each side, keeping medium rare on the inside, making sure you don’t burn your sesame seeds either. Remove and transfer immediately to a cutting board.

Let your ahi rest for at least 5 minutes, and then thinly slice into ¼-inch slices, you want it pretty thinly sliced.

While your ahi is resting, make your sauce. In a small serving bowl, toss together soy sauce, chili flakes, vinegar, and black pepper.

Transfer your sliced ahi onto a platter, placing your sauce on the plate for dipping. You can also go ahead and pour the sauce mixture over the ahi directly. Top with thinly sliced scallions.