Prepare the Marinade
In a small bowl, whisk together olive oil, sesame oil, ground ginger, soy sauce, garlic powder, rice vinegar, and half of the sesame seeds.
Marinate the Tuna
Pour half of the marinade over the tuna steaks and reserve the remaining marinade.
Cover and refrigerate for at least 20 minutes (or up to overnight).
Preheat the Grill
Preheat your grill to medium-high heat (about 350°F).
Coat the Tuna
Remove the tuna steaks from the marinade and discard the used portion.
Coat the tuna with 1 tablespoon (or more) of sesame seeds to form a crust.
Grill the Tuna
Place tuna steaks on the hot grill. Cook for 2–3 minutes per side.
Drizzle a little of the reserved marinade over the steaks while grilling.
For medium-rare, cook until the internal temperature reaches 135°F. For well-done, cook to 145°F as per FDA guidelines.
Serve and Enjoy
Remove from the grill. Top with remaining marinade, sliced green onions, and additional sesame seeds.
Serve immediately.
Notes
Marinating longer enhances flavor, but 20 minutes is sufficient if short on time.
For tender, medium-rare tuna, cook to 135°F; cook to 145°F for well-done.
Pairs well with rice, stir-fried vegetables, or salad for a complete meal.