01 -
In a small bowl, whisk together soy sauce, sesame oil, brown sugar, pressed garlic, and grated ginger until sugar is dissolved.
02 -
Rinse tuna steaks and pat thoroughly dry with paper towels. Season both sides lightly with salt and freshly ground black pepper.
03 -
Heat a large skillet over high heat. Add grapeseed oil and swirl to coat. Once the oil is shimmering, carefully place the tuna steaks in the skillet. Sear for 2 minutes on the first side.
04 -
Flip tuna steaks and continue cooking for 1 minute. Spoon half of the prepared marinade into the pan during the final minute to glaze the tuna.
05 -
Transfer tuna steaks to a cutting board. Slice thinly, or leave whole if preferred. Drizzle with remaining unused marinade and sprinkle mixed sesame seeds evenly over the top before serving.