Pit olives and coarsely chop. In a bowl stir together olives, onion, oregano, oil, pepper, and salt to taste. Pat steaks dry and season with salt and pepper. Grill steaks on an oiled rack set 5 to 6 inches over glowing coals about 4 minutes on each side for medium-rare. (Alternatively, grill steaks in a hot oiled well-seasoned ridged grill pan over moderately high heat.)