Place ribs in a large roasting pan. Pour vinegar over ribs. Rub ribs with seasoned salt and pepper. Separate onion into rings, and place atop ribs. Bake, covered, at 400º for 2 1/2 hours; drain. Return ribs and onion to roasting pan. Pour Chipotle Barbecue Sauce over ribs, turning to coat.
Bake, uncovered, 25 more minutes.