Combine sesame seeds in a shallow dish. Pat the tuna steaks dry and rub both sides with 1 1/2 Tablespoons vegetable oil. Sprinkle with salt and pepper and press both sides and edges of the tuna steaks in the sesame seeds.
Heat the remaining oil in a large non-stick skillet over high heat until oil is just beginning to smoke. Add the tuna steaks. Cook 30 seconds without moving, reduce the heat to medium-high. Cook a total of 1 1/2 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. Sesame seeds should be golden.
Cut tuna steaks in 1/4-inch slices and serve topped with Wasabi Horseradish Cream Sauce.