Preheat grill to high. Melt butter with garlic. Reserve.
Rub both sides of each steak with toasted sesame oil (just enough to coat it slightly). Combine garlic powder, chipotle and grill seasonings, and pepper in a small bowl. Season both sides of the steaks with the spice mixture, pressing gently to make sure the spices stick.
Using tongs, place steaks on the hot grill. Do not move for at least 3 minutes or you will mess up the grill marks. Cook until it is done to your liking (generally 5-12 minutes/per side, depending on the thickness of the steak) then flip over and cook the other side. When the steaks have finished cooking, remove to a cutting board and let rest.