Baby Back Ribs With Mustard Sauce

1/3 cup Brown sugar
1/4 cup Onion, finely chopped
1/4 cup Vinegar
1/4 cup Mustard
1/2 teaspoon Celery seed
1/4 teaspoon Garlic powder
4 pounds Pork spareribs, or pork loin ribs, cut into pieces

For sauce, in a saucepan combine brown sugar, onion, vinegar, mustard, celery seed and garlic powder. Bring to boiling, stirring till sugar dissolves. Preheat grill. Adjust heat for indirect cooking. Place ribs on grill rack over medium heat. Cover and grill for 1 1/4 to 1 1/2 hours or till ribs are tender and no pink remains. Brush occasionally with sauce the last 15 minutes of grilling.