In a small nonstick skillet, heat oil over medium-low heat until hot. Add garlic. Cook and stir 4-5 minutes or until tender, but not browned. Add onions. Continue cooking and stirring 4-5 minutes or until onions are tender. Season with salt and pepper; cool completely.

 

Meanwhile with a sharp knife, cut a pocket in each beef steak. Start 1/2 inch from one long side of steak and cut horizontally through center of steak to within 12 inch of each side. Spread half of garlic mixture inside each steak pocket. Secure opening with wooden toothpicks.

 

Preheat broiler. Position broiler pan so surface of steak is 5 inches from heat source. Broil until top side is brown; approximately 12 minutes. Turn and brown other side for 12-13 minutes for medium doneness.