HEAT grill to medium-high heat.
MIX first 4 ingredients; shape into 8 (1/2-inch-thick) patties.
GRILL 4 to 6 min. on each side or until done (160ºF), turning and brushing occasionally with 1/4 cup barbecue sauce for the last few minutes.
SPREAD buns with remaining barbecue sauce; fill with lettuce, tomatoes and burgers.