1 lb. ground beef
1/4 cup KRAFT Original Barbecue Sauce
1 medium red onion, cut into 4 slices
1/4 cup KRAFT Zesty Italian Dressing, divided
4 KRAFT Singles
4 lettuce leaves
4 slices tomato (about 1 medium)
4 hamburger buns, split, grilled
PREHEAT grill to medium-high heat. Mix meat and barbecue sauce; shape into four patties. Brush onion slices with 2 Tbsp. of the dressing.
GRILL patties and onions 5 min. on each side or until patties are cooked through (160°F) and onions are tender, brushing onions occasionally with remaining 2 Tbsp. dressing. Top each patty with Singles; grill an additional 1 to 2 min. or until Singles begin to melt.
PLACE 1 lettuce leaf, 1 tomato slice and burger on bottom half of each bun. Cover with onions and tops of buns.