Combine sauce ingredients in a large sturdy ziplock bag. Place ziplock upright in a large shallow dish. Cut slab into individual ribs and place them inside the bag. Close bag removing as much air as possible. Turn bag several times to thoroughly coat all the ribs. Place dish in the refrigerator for at least 3 hours or overnight.

Line shallow baking pan with heavy duty foil, extending foil up over the sides and ends of pan so you will have plenty to enclose ribs. Arrange marinated ribs in a single layer on foil and pour any remaining marinade over them. Fold foil over ribs and then cover pan with another piece of foil, sealing tightly.

Place pan in a 300 degree oven. After 3 hours, reduce heat to 250 and continue to bake for 30-60 minutes. When ready to eat, uncover ribs and turn over so the saucy side is facing up. Place under the broiler for 3-5 minutes to char if desired.