Preheat oven to 300 degrees F. Place ribs meat-side up in a large roasting pan.
In a small bowl, combine garlic powder, paprika, salt, and pepper. Sprinkle ribs with spice mixture, then cover tightly with aluminum foil.
Roast 2-1/2 hours.
Meanwhile, in a medium bowl, combine remaining ingredients; mix well and set aside.
Preheat grill to high heat. Brush ribs with sauce and cook on grill until sauce begins to caramelize. Cut into individual ribs and serve with remaining sauce.