Caramelized Onion Soup

Long, slow cooking is the secret to perfect caramelized onions, and a slow cooker is a great way to get the job done. Use the first part of the recipe to make just the caramelized onions to use in other recipes, or add the broth and other ingredients to make a rich-tasting onion soup. Use a gluten-free bread to make this recipe gluten-free. To make this recipe soy-free, omit the Worcestershire sauce and use a soy-free sauce (purchased or homemade) or add some soy-free vegetable broth base o