Not hard at all to make yourself. Tuna is not cheap but doing it at home is cheaper than a restaurant.

2 (6-8 ounce) ahi tuna steaks (3/4 of an inch thick)
2 Tbsp dark sesame oil
2 Tbsp soy sauce (or 2 teaspoons of wheat-free tamari for gluten-free option)
1 Tbsp of grated fresh ginger
1 clove garlic, minced
1 green onion (scallion) thinly sliced (a few slices reserved for garnish)
1 teaspoon lime juice

Note* I didnt have scallions.
Crushed sesame seeds and fresh ground pepper

1 Mix the marinade ingredients together and coat the tuna steaks with the marinade, cover tightly, and refrigerate for at least an hour.

1a. Roll the tuna edgewise in the crushed sesame and pepper.

2 Heat a non-stick skillet over medium high to high heat. When the pan is hot, sear them for a minute to a minute and a half on each side ( even a little longer if you want the tuna less rare .)

3 Remove from pan and slice into 1/4-inch thick slices. We served it with some wasabi, Thai chile sauce and soy sauce.

Marinated, coated and searing!