Ingredients
Sauce Base
- 3 tablespoons butter
- 2 medium onions, sliced
- 1 teaspoon sugar
Liquids and Flavorings
- 2 tablespoons brandy
- 1 tablespoon flour
- 2 ½ cups beef broth
- 2 teaspoons soy sauce
- 2 teaspoons Worcestershire sauce
- salt and pepper to taste
For Serving
- sliced French bread
- 2 slices Gruyere cheese (or Swiss cheese)
Instructions
- Caramelize Onions: In a medium enamel-coated cast iron soup pot, melt the butter over medium-low heat. Add the sliced onions, stir to coat them thoroughly in the butter, then sprinkle in the sugar. Cook the onions slowly over medium-low heat, stirring every 10 minutes, until they turn a deep golden brown, about 25-30 minutes. Adjust heat as needed to avoid burning and ensure slow caramelization.
- Deglaze the Pan: Once the onions are caramelized, pour in the brandy to deglaze the pan. Stir continuously and scrape the bottom of the pot with a wooden spoon to loosen any browned bits, which add rich flavor to the soup.
- Add Flour: Sprinkle in the flour and cook, stirring constantly, for 1 minute to remove the raw flour taste and help thicken the soup.
- Add Broth and Seasonings: Pour in the beef broth, then add soy sauce and Worcestershire sauce. Bring the soup to a gentle simmer, taste, and season with salt and pepper as desired. Let it cook gently for 10 minutes to meld the flavors.
- Prepare Bread and Cheese: While the soup simmers, toast the French bread slices until crisp. Ladle the hot soup into two bowls, top each with the toasted bread slices, then place two slices of Gruyere cheese over the bread in each bowl.
- Melt Cheese: Melt the cheese on top of the soup either under the oven broiler or in the microwave. Alternatively, use a chef’s torch to achieve a bubbly, melted finish. Serve immediately for a warm, comforting meal.
Notes
- For a vegetarian version, substitute the beef broth with vegetable broth and omit Worcestershire sauce or use a vegetarian alternative.
- Adjust the cooking time for the onions if your stove runs hotter or cooler to prevent burning.
- Brandy can be omitted if preferred; alternatively, use sherry or white wine for deglazing.
- Gruyere cheese melts best and adds the authentic flavor, but Swiss cheese is a suitable substitute.
- For extra flavor, you can add a sprig of thyme while simmering the soup and remove it before serving.
- Prep Time: 10 minutes
- Cook Time: 45 minutes
- Category: Soup
- Method: Stovetop
- Cuisine: French