- 1/4 cup tamari (gluten-free soy sauce)
- 1/4 cup sesame oil
- 2 tablespoons mirin (Japanese sweet wine)
- 2 tablespoons honey
- 2 tablespoons rice wine vinegar
- 2 tablespoons grated fresh ginger
- 2 green onions, thinly sliced, divided
- 2 cloves garlic, minced, or more to taste
- 4 (6 ounce) tuna steaks
- 2 tablespoons sesame seeds, or to taste
- 1 tablespoon olive oil
- Whisk tamari, sesame oil, mirin, honey, vinegar, ginger, green onions, and garlic together in a bowl until marinade is evenly mixed. Place tuna steaks in the marinade and refrigerate for at least 1 hour.
- Spread sesame seeds onto a plate. Remove tuna from marinade and discard marinade. Press tuna into sesame seeds until evenly coated.
- Heat olive oil in a cast iron skillet over high heat until very hot; cook tuna in the hot oil until cooked to desired doneness, 30 seconds to 5 minutes per side.