Product Recall: Kraft and Polly-O String Cheese and String Cheese Twists. Click here
HEAT grill to medium heat.
GRILL patties 5 min. on each side or until done (160ºF).
MEANWHILE, heat oil in large skillet on medium-high heat. Add onions; cook and stir 10 min. or until golden brown, stirring frequently. Stir in steak sauce.
FILL buns with tomatoes, burgers, Singles and onion mixture.