Bbq cheeseburgers

1-1/2 lb ground beef
1/4 cup finely chopped onion
Prepared barbecue sauce
4 slices process American cheese
4 crusty rolls, split
Romaine lettuce
Tomato slices

In large bowl, combine ground Beef and onion, mixing lightly but thoroughly. Shape into four 3/4"-thick patties. Place patties on grid over medium, ash-covered coals. Grill, uncovered, 13 to 15 minutes or until centers are no longer pink, turning occasionally. Approx. 1 minute before burgers are done, brush with barbecue sauce; top with cheese. Line bottom of each roll with lettuce and tomato; top with cheeseburger. Close sandwiches.