PREPARATION:

1. Prepare grill for direct grilling. Combine ground beef and 2 tablespoons barbecue sauce in large bowl. Shape into six 1-inch-thick patties.
2. Place patties on grid over medium heat. Grill, covered, 8 to 10 minutes (or, uncovered, 13 to 15 minutes) for medium doneness or until 160°F in centers of patties, turning and brushing often with remaining barbecue sauce.
3. Meanwhile, brush tomato and onion slices* with oil. Place on grid. Grill tomato slices 2 to 3 minutes and onion slices about 10 minutes.

   *Onion slices may be cooked in 2 tablespoons oil in large skillet over medium heat 10 minutes until tender and slightly brown.

4. Just before serving, place rolls, cut side down, on grid; grill until lightly toasted. Serve patties on rolls with tomatoes, onions and lettuce.