To be at its best, the tuna should be cooked on the outside but almost raw (just warm) in the middle.

1. Combine the sesame seeds in a shallow dish.
2. Pat the tuna steaks dry and rub both sides with 1 ½ tbsp. vegetable oil.
3. Sprinkle with salt and pepper and press both sides and edges of the tuna steaks in the sesame seeds.
4. Heat the remaining oil in a large nonstick skillet on high heat until the oil just begins to smoke. Add the tuna steaks. Cook 30 seconds without moving, reduce the heat to medium-high. Cook a total of 1 ½ minutes on each side for rare or 3 minutes on each side for medium rare, being careful when turning the steaks not to disturb the crust. The sesame seeds should be golden.
5. Cut the tuna steaks into 5 mm (¼ inch) slices and serve topped with wasabi horseradish cream sauce.