Bake 40 to 45 min. or until potatoes are tender and lightly browned, brushing potatoes with remaining barbecue sauce mixture and increasing oven temperature to 425ºF after 30 min. After about 20 min., heat oil in small skillet on medium heat. Add onions; cook 10 to 15 min. or until lightly browned, stirring occasionally. Add sugar; mix well. Cook 5 min., stirring frequently.