1Heat gas or charcoal grill. In small bowl, toss coleslaw mix and onion with dressing; set aside.
2In medium bowl, mix remaining ingredients except buns. Shape mixture into 4 patties, about 3/4 inch thick.
3Carefully brush oil on grill rack. Place patties on grill over medium heat. Cover grill; cook 10 to 14 minutes, turning once, until thermometer inserted in center of patties reads 165°F. During last 2 minutes of grilling, place buns, cut sides down, on grill.
4Place burgers on bun bottoms. Using slotted spoon, top each burger with about 1/3 cup coleslaw mixture. Cover with bun tops.