Keep the tuna cold in the refrigerator right up until you are ready to cook.

Squeeze the fresh mandarin orange juice and pulp into a bowl, or peel and chop, using the side of a broad knife to scoop up the fruit and juices into a bowl. Add the garlic, ginger, white portion of the scallion, soy sauce, honey, rice vinegar, and sesame oil. Mix well and set aside with the green parts of the chopped scallion.

On your serving plate(s), fan out the sliced avocado and squeeze a little lime juice over the top so they don’t turn brown. Place another lime wedge on the side of the plate for serving. You can do this on one family-style plate or individual plates like we did.

Lightly rub the salt on both sides of the tuna filets. Coat each side with sesame seeds. Optionally, you can also coat the sides of the filets so they’re totally covered.

Heat a cast iron or carbon steel skillet until lightly smoking, and coat the pan in oil. It should be VERY HOT. Gently lay the tuna steaks in the pan, without disturbing them. Sear for 30 to 60 seconds each side (shorter for rare tuna, longer for medium rare).

Transfer the fish to a cutting board, and let it rest for 2 minutes before slicing. Use a very sharp knife to slice the tuna at a slight angle into ½-inch slices. Place the sliced tuna over the sliced avocado.

Spoon the sauce over the tuna, and top with the chopped scallion greens and a pinch of flaky salt if using. Serve immediately, and squeeze additional lime juice over the top if desired!