Meanwhile, for sauce, heat oil in a saucepan. Cook and stir onion and garlic for 5 minutes or until tender. Stir in tomato sauce, rum, molasses, Worcestershire sauce, vinegar, dry mustard, and chili powder. Bring to boiling; reduce heat. Simmer, uncovered, for 20 minutes or until reduced to 1-1/2 cups, stirring occasionally.
To serve, cut ribs into six portions. Spoon sauce over ribs. Makes 6 servings.