Preheat the oven to 400°F (200°C).

In a mixing bowl, whisk together the olive oil, soy sauce, lemon juice, garlic, and ginger.

Place the ahi tuna steaks in a shallow dish and pour the marinade over them. Let them marinate for at least 10 minutes.

Cover a baking sheet with parchment paper.

Remove the tuna steaks from the marinade and place them on the prepared baking sheet.

Sprinkle sesame seeds over the tuna steaks.

Bake the tuna in the preheated oven for 12-15 minutes, until opaque but slightly pink in the center.

Remove the tuna from the oven and let it rest for a couple of minutes before serving.