Homesteader's Four-Bean Casserole

8 bacon slices
3 to 4 medium onions, cut into rings and separated
½ to ¾ cup maple syrup or packed dark brown sugar
1½ teaspoons garlic powder
1 teaspoon dry mustard
¼ cup cider vinegar
1 (15-ounce) can dark red kidney beans, drained
1 (15-ounce) can lima beans, drained
1 (16-ounce) can butter beans, drained
1 (16-ounce) can baked beans, undrained

1. Cook bacon in a large skillet over medium-high heat until crisp. Remove and drain on paper towels; crumble and set aside.
2. Add onions, syrup, garlic powder and dry mustard to pan drippings. Reduce heat to medium and add vinegar slowly, taking care because hot steam will rise. Cover and cook 20 minutes.
2. Preheat oven to 350F. Grease a 3-quart casserole or 13 x 9-inch baking dish.
3. Add beans to pan. Stir in onion mixture and bacon; mix well. Cover and bake 45 minutes. Remove from oven, uncover, and let stand 20 to 25 minutes before serving. Serves 12.

The onion mixture will harden when added to the beans, but will break down during the baking process.