Preheat grill to medium-high (350 degrees F)

In a small bowl, mix olive oil, sesame oil, ginger, soy sauce, garlic powder, rice vinegar, and half sesame seeds.

Pour half sauce over tuna steaks, and reserve half for finishing tuna.

Let fish marinate, refrigerated, for at least 20 minutes (as grill comes to temperature) up to overnight.

When grill is scorching hot, remove tuna steaks from the marinade and discard excess the mariande fish was sitting in.

Cover fish with 1 tablespoon of sesame seeds to make a "crust" before grilling. Add more than 1 tablespoon if needed.

Place steaks on grill.

Grill 2-3 minutes per side, drizzling a bit of reserved sauce on top of fish as it cooks, until fish is charred on each side.

For medium-rare tuna steaks, cook to 135 degrees F. The FDA recommends 145 degrees F.

Remove tuna from grill, and top with reserved sauce, green onions, and additional sesame seeds.

Enjoy!