MIX first 5 ingredients until blended; pour over chicken in shallow dish. Turn to even coat both sides of each wing. Refrigerate 30 min. to marinate.
HEAT grill to medium-high heat. Remove chicken from marinade; discard marinade. Grill chicken 15 min., turning occasionally. Brush lightly with some of the barbecue sauce; grill 4 to 5 min. or until chicken is done, turning and brushing frequently with remaining barbecue sauce.
PLACE chicken on platter; top with onions.