Hot and Spicy Ribs

1/4 cup finely chopped onions
1 clove garlic, minced
1 tablespoon butter
1 cup bottled barbecue sauce
2-3 teaspoons chili powder
1 teaspoon prepared mustard
1/4 teaspoon fresh ground pepper
4 lbs meaty pork spareribs

1. In a small saucepan cook onion and garlic in hot butter until tender.
2. Add remaining ingrediants except ribs and bring to a boil.
3. Reduce heat and simmer, uncovered, for 15 minutes, stirring occasionally.
4. Meanwhile, preheat a grill to medium-hot and prepare for indirect cooking.
5. Place ribs bone-side down on grill rack.
6. Cover and grill for 1 1/4 to 1 1/2 hours or until ribs are tender, brushing with sauce the last 15 minutes of grilling.