Combine beer and steak sauce in 1-cup glass measure. Cover and microwave on HIGH 1 to 1-1/2 minutes or until bubbly.
Lightly shape ground beef into four 3/4-inch thick patties. Place patties in center of grid over medium, ash-covered coals; arrange onion around patties. Grill, covered, 11 to 15 minutes (over medium heat on preheated gas grill, 13 to 14 minutes) until in
Serve burgers and onions in rolls with lettuce and sauce.