Preheat oven to 300 degrees F (150 degrees C). Place ribs on a rack in a shallow roasting pan. Scatter 4 cloves of sliced garlic over ribs. Cover, and bake for 2 1/2 hours. Cool slightly.
In a small bowl, mix together white sugar, paprika, salt, black pepper, chili powder, and ground cumin. Rub spices over cooled ribs. Cover, and refrigerate overnight.
In a small saucepan, mix together brown sugar, cider vinegar, ketchup, chili sauce, Worcestershire sauce, lemon juice, onion, dry mustard, and 1 clove garlic. Simmer over medium-low heat, uncovered, for 1 hour. Reserve a small amount for basting; the remainder is a dipping sauce.
Preheat grill for medium heat.
Place ribs on grill. Grill, covered, for about 12 minutes, basting with the reserved sauce, until nicely browned and glazed. Serve with remaining sauce for dipping.
