1) Place sesame seeds in un-greased pan. Roast over medium heat for 1 minute, shaking the pan occasionally. Remove the pan immediately.
2) Place sesame seeds, 2 tsp. salt, 1 tsp. black pepper on a plate.
3) Drizzle olive oil on both sides of tuna steaks and spread evenly with hand.
4) Sprinkle remaining salt and pepper on both sides.
5) Place on hot grill. Grill evenly on each side. 1 1/2 minutes for rare. 3-4 for minutes for medium. 5 minutes each side for well-done.
6) Remove from heat immediately and serve.