Go Back

Vegetarian French Onion Soup

This onion soup is made vegetarian by using mushroom broth instead of beef broth, but don't worry, it tastes just as good! Top with fresh bread and a generous amount of cheese, bake until the cheese has melted and has turned lightly golden and bubbly. Enjoy every spoonful. 
Course Appetizer, Soup
Cuisine French, vegan, vegetarian
Prep Time 15 minutes
Cook Time 50 minutes
Total Time 1 hour 5 minutes
Servings 4


  • 4 tablespoons butter or soft margarine
  • 4 medium yellow onions, peeled and sliced into half-moons
  • 2 large garlic cloves
  • 1/2 cup dry red wine
  • 1 tablespoon flour
  • 8 cups mushroom or vegetable broth, low-sodium
  • 1 teaspoon Worcestershire sauce (optional)
  • 3 sprigs fresh thyme
  • 1 bay leaf
  • 1 teaspoon fine grain sea salt, to taste
  • french bread, such as baguette
  • 1 1/2 cups Grated cheese (old white cheddar, gruyere, swiss or mozzarella works)


  • Heat butter/margarine in a large saucepan over medium heat. 
  • Add onions and stir to coat with butter/margarine. Cook for 30 minutes, stirring every few minutes to avoid sticking. The onions should slowly brown, without getting burnt.
  • After 30 minutes. stir in the garlic and salt and cook for another minute. Using a wooden spoon, scrape up any pieces sticking to the pan.
  • Slowly stir in the wine to deglaze the pan. Stir in the flour, followed by the broth, Worcestershire sauce, thyme and bay leaf.
  • Bring the soup to a boil, then reduce heat to low-medium and simmer for 10 minutes, covered. Meanwhile, preheat oven to 400F. 
  • Remove the sprigs of thyme and bay leaf using a spoon. Spoon the soup in oven-safe bowls. Top with a slice of french bread and a sprinkle of cheese (approximately 1/4 cup on each).
  • Bake for 6 minutes, then broil until golden and bubbly, being careful it doesn't burn. Serve immediately.


Use dry red or white wine, whichever one you prefer.
I use whole wheat flour, but white flour works as well. I haven't tried a gluten-free flour, but for a gluten-free option, omit the flour.
Feel free to use beef or vegetable broth if preferred. I tend to use half mushroom and half vegetable broth as my vegetable broth is salt-free and it helps reduce the salt in the recipe. You can use low-sodium mushroom broth if available. Adjust the salt to taste.
Store leftover soup in the fridge. When ready to eat, heat up your soup, then transfer to an oven safe bowl and bake with the bread and cheese as directed. I don't recommend storing leftovers with the baked bread and cheese on top.