Vegetarian French Onion Soup
This Vegetarian French Onion Soup swaps the traditional beef broth for a rich vegetable and mushroom broth, without losing any of the deep, caramelized flavor that makes French onion soup so beloved. Sweet onions cook low and slow until they turn a deep amber, then simmer in a savory broth spiked with dry sherry and fresh thyme. A thick slice of toasted baguette and a blanket of melted Gruyere cheese finish each bowl under the broiler.
Equipment
- Dutch oven or other heavy bottomed pot Enameled cast iron recommended for even heat distribution
- Mandoline slicer For evenly thin onion slices
- Broiler safe soup crocks or oven proof bowls Stoneware recommended
- Sharp chef's knife
- Wooden spoon
- Ladle
- Baking sheet
Ingredients
- 4 tablespoons unsalted butter
- 1 tablespoon olive oil
- 3 pounds yellow onions about 6 large onions, thinly sliced
- 1 teaspoon salt plus more to taste
- 1/2 teaspoon sugar helps the onions caramelize
- 3 cloves garlic minced
- 2 tablespoons all purpose flour
- 1/2 cup dry sherry or dry white wine
- 6 cups vegetable broth
- 2 cups mushroom broth or extra vegetable broth
- 2 bay leaves
- 4 sprigs fresh thyme plus more for garnish
- 1 tablespoon vegetarian Worcestershire sauce
- 1/2 teaspoon black pepper
- 1 baguette sliced into 1/2 inch rounds
- 2 cups shredded Gruyere cheese
- 1/2 cup grated Parmesan cheese optional
Instructions
- Peel and thinly slice the onions, then mince the garlic.
- Melt butter with olive oil in a Dutch oven over medium heat. Add onions, salt, and sugar, then cook for 15 minutes until softened. Reduce heat to medium-low and cook for 35-45 minutes, stirring occasionally, until deep golden brown.
- Add garlic and cook for 1 minute. Stir in flour and cook for 2 minutes. Pour in sherry and deglaze the pot, simmering for 2-3 minutes. Add vegetable broth, mushroom broth, bay leaves, thyme, Worcestershire sauce, and pepper.
- Bring soup to a gentle boil, then reduce heat to low and simmer partially covered for 25-30 minutes. Season with salt and pepper to taste. Remove bay leaves and thyme sprigs.
- Preheat broiler and arrange baguette slices on a baking sheet. Broil for 1-2 minutes per side until lightly golden and crisp.
- Ladle hot soup into broiler safe bowls. Top each with 1-2 toasted baguette slices and sprinkle generously with Gruyere and Parmesan. Broil for 2-4 minutes until cheese is melted and bubbly. Let cool slightly before serving.
Notes
- Do not rush the caramelizing step - low and slow heat is what builds real flavor in the onions. This can take up to 45 minutes total.
- Use a wide, heavy bottomed pot so the onions have room to spread out and brown evenly.
- Deglaze with a splash of broth anytime the pot looks dry or the onions start sticking too much.
- Let the broth simmer uncovered for the last 10 minutes if it seems thin, to help it reduce slightly.
- Grate your own Gruyere from a block for smoother, more even melting under the broiler.
- Store the soup base in an airtight container in the refrigerator for up to 4 days. Keep bread and cheese separate until serving.
- Freeze the soup base, without bread or cheese, in a freezer safe container for up to 2 months.
- To make this soup vegan: swap butter for olive oil and use a good melting vegan cheese. Double check that your Worcestershire sauce is vegan.
- Swap in shallots for half the onions for a slightly sweeter, milder flavor. Use cognac or brandy instead of sherry for a deeper finish.
- Stir in a spoonful of miso paste along with the broth for extra umami depth, or add a splash of balsamic vinegar near the end for tang.
Nutrition
Serving: 1BowlCalories: 340kcalCarbohydrates: 34gProtein: 12gFat: 17gSaturated Fat: 9gPolyunsaturated Fat: 1gMonounsaturated Fat: 5gCholesterol: 45mgSodium: 820mgPotassium: 420mgFiber: 4gSugar: 12gVitamin A: 8IUVitamin C: 15mgCalcium: 25mgIron: 8mg
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