In a shallow dish or non-reactive pan, whisk together the tamari soy sauce, rice vinegar, mirin (or sake), jaggery, and Kashmiri red chili pepper until the mixture is smooth and well combined. Lay the tuna steaks in the marinade, turning them once to ensure both sides are evenly coated. Cover and refrigerate for about 20 minutes to allow the flavors to begin infusing.

After 20 minutes, flip the tuna steaks to marinate the other side and refrigerate for another 20 minutes. Meanwhile, pour the sesame seeds into a small bowl and keep them ready for coating.

When the marinating time is complete, remove the tuna steaks from the dish and discard the leftover marinade. Press the sesame seeds gently into both sides of each steak, ensuring an even layer that will form a delicate crust when cooked. Use about 2 teaspoons per side or more for a thicker coating.

Preheat a grill or a heavy-bottomed skillet over medium-high heat. Once hot, place the sesame-crusted tuna steaks onto the grill. Cook each side for 1–3 minutes, depending on your desired doneness — shorter for a rare center, longer for medium. The exterior should develop a light golden sear while the inside remains tender.

Transfer the cooked tuna steaks to a plate. Spoon a small amount of melted garlic ghee over each steak, allowing it to melt and infuse the fish with rich, aromatic flavor. Let the tuna rest for a few minutes before serving.

Finish with a drizzle of extra tamari and a touch of freshly ground black pepper. Serve warm with your favorite side salad, steamed rice, or grilled vegetables for a complete, flavorful meal.