Good-Cooking - Apple Orchard Barbecue Sauce

Ingredients

• 1 medium onion, grated or finely chopped
• 4 cups pressed apple cider (not pasteurized apple juice)
• 1/2 cup cider vinegar
• 1/2 cup firmly packed dark brown sugar
• 1 tablespoon whole mustard seed
• 1 teaspoon celery salt or celery seed
• 1 tablespoon Worcestershire sauce
• 1 tablespoon liquid smoke
• 2 (12 ounce) bottles chili sauce
• Hot pepper sauce, to taste (optional)