Maple-Barbecued Oven Spareribs

1 1/2 cups maple syrup

2 tablespoons chili sauce

2 tablespoons cider vinegar

1 1/2 tablespoons onion -- chopped

1 tablespoon Worcestershire sauce

1 teaspoon salt

1/2 teaspoon dry mustard

1/8 teaspoon black pepper

2 pounds pork spareribs

Combine all ingredients except spare ribs and bring to a boil. Wipe spareribs with damp paper towels. Brush sauce on both sides of ribs. Place in a shallow, open roasting pan and bake for 1-1/2 hours, basting frequently with remaining sauce and turning to glaze.