Barbecue sauce is not just for pork or chicken! I make baked beans and sloppy joes with it, and even use it as a sauce for grilled portobello mushrooms.
1. Sauté the onions in a large saucepan over medium heat, stirring occasionally, for 7 to 8 minutes, until they start to turn brown and translucent. Add water 1 to 2 tablespoons at a time as needed, to keep the onions from sticking to the pan. Add the garlic and cook for 1 minute more.
2. Stir in the tomato sauce, vinegar, Worcestershire sauce, maple syrup, molasses, mustard, pepper to taste, and 1 cup of water, and bring to a boil over high heat. Reduce the heat to low and simmer, stirring often to prevent scorching, for about 45 minutes, until thickened. Taste and adjust the seasoning. If desired, transfer the sauce to a blender and puree until smooth (or use an immersion blender).
3. Store in an airtight container in the refrigerator for up to 7 days.