Heat a dry skillet over medium heat for 2-3 minutes. Add white and black sesame seeds, stirring constantly until fragrant and lightly golden. Remove from heat and pour onto a plate.
2 tablespoons white sesame seeds, 2 tablespoons black sesame seeds
Mix soy sauce, sesame oil, grated ginger, and garlic in a small bowl. Add the tuna steaks and turn to coat all sides. Let sit for 10-15 minutes at room temperature.
1 tablespoon soy sauce, 1 teaspoon sesame oil, 1 teaspoon fresh ginger, 0.5 teaspoon garlic, 2 pieces fresh tuna steaks
Remove tuna from marinade and pat completely dry with paper towels. Press both sides firmly into the toasted sesame seeds until evenly coated. Season lightly with salt and pepper.
2 pieces fresh tuna steaks, 2 tablespoons white sesame seeds, 2 tablespoons black sesame seeds, to taste salt, to taste black pepper
Heat a cast iron skillet over medium-high heat for 3-5 minutes. Add a thin layer of oil. Place tuna steaks with 1 inch between pieces. Sear for 1.5-2 minutes per side for rare or 2.5-3 minutes per side for medium-rare, until crust is golden and crisp.
2 pieces fresh tuna steaks
Transfer tuna to a cutting board and let rest for 3-5 minutes to finish cooking without drying out. Slice against the grain into ½-inch pieces. The center should remain pink and the edges opaque. Optionally drizzle lemon or lime juice before serving.
2 pieces fresh tuna steaks, to taste lemon or lime juice
