Rich and hearty, this Vegetarian French Onion Soup is a bowl full of delicious comfort.
Although the ingredients are classic and humble—oil, butter, onions, broth—I used to think of French onion soup as something to be eaten only on special occasions. But when I realized it was just as easy to make as some of my other favorite soups, and that a vegetarian version could deliver the same depth and richness without beef broth, I started making it all the time.
French onion soup has been around for centuries, dating back to ancient times when onion-based broths were a staple for their affordability and accessibility. The version we recognize today, with deeply caramelized onions and a flavorful broth, gained popularity in 19th-century Paris, particularly in the bustling markets of Les Halles. There’s a charming but questionable tale that King Louis XV—or perhaps Stanisław Leszczyński, the Duke of Lorraine—first created the soup with just onions, butter, and champagne. While history is a bit unclear on that front, one thing is certain: French onion soup has stood the test of time, and a meatless version is just as satisfying and full of flavor.
Tips For A Perfect Vegetarian French Onion Soup
While this is a simple and straightforward recipe, patience is key, starting with caramelizing your onions. Use all yellow onions, as the recipe suggests, or mix in white or red for a more complex flavor. Slice them very thinly (a mandoline helps!) and take your time. Good caramelization is what gives this soup its deep, rich taste.
When deglazing, use a good-quality dry white wine—one you’d actually drink—to lift those delicious browned bits from the bottom of the pan. If you love a little tang, balsamic vinegar adds wonderful depth, but apple cider or red wine vinegar can also help balance the sweetness of the onions.
Finally, once you’ve topped each bowl with a toasted baguette slice and melted that salty, nutty Gruyère cheese under the broiler, serve the soup immediately. The contrast of the crisp bread, gooey cheese, and rich broth is what makes every bite irresistible.
Ingredients
- 3 tablespoons olive oil
- 3 tablespoons unsalted butter
- 3 pounds yellow onions thinly sliced
- 1 1/2 teaspoons granulated sugar
- 2 cloves garlic minced
- 1/3 cup dry white wine
- 8 cups low-sodium vegetable broth
- 2 teaspoons balsamic vinegar
- 1 bay leaf
- 1 1/2 teaspoons dried thyme
- Kosher salt and black pepper to taste
- 4 slices of baguette
- 1 cup grated Gruyère cheese
How To Make Vegetarian French Onion Soup
Step 1: In a large pot, heat oil and butter over medium heat. Add the thinly sliced onions and cook, stirring occasionally, for about 20 minutes.
Step 2: Add the sugar and cook for another 20 minutes or until the onions are caramelized and golden brown.
Step 3: Stir in the minced garlic and cook for 2 minutes. Deglaze the pot by adding the white wine and scraping the bottom of the pot to loosen any browned bits.
Step 4: Add the vegetable broth, balsamic vinegar, bay leaf, dried thyme, salt, and pepper. Bring to a simmer and cook for 30 minutes.
Step 5: Meanwhile, preheat the oven to 400°F. Place the baguette slices on a baking sheet and toast in the oven for about 8-10 minutes, until crispy and golden. Remove from the oven.
Step 6: Adjust the soup seasoning as needed with more salt or balsamic vinegar. Ladle the hot soup into oven-safe bowls. Top each with a slice of toasted baguette and sprinkle generously with grated Gruyère cheese.
Step 7: Place under the broiler for 3-4 minutes, or until the cheese is melted and bubbly.
FAQs & Tips
How Do I Store Leftovers?
Cool your vegetarian French onion soup, and you can store it, without the toasted baguette and cheese on top, for up to 5 days in an airtight container in the fridge. You can also freeze the soup (again without the cheese and bread topping) for up to 3 months; thaw frozen soup overnight in the fridge before reheating.
Is This Recipe Vegan?
Not quite, but it can be by simply substituting plant-based butter for dairy butter and omitting the cheese topping.
Do Other Kinds Of Cheese Work In This Recipe?
Gruyère is traditional, but you can use any kind of cheese you like. Just make sure it is a cheese that melts well, such as fontina or provolone.
Serving Suggestions
French onion soup is often served as a first course in French restaurants, so something I love to do with this vegetarian version is follow it with a meatless meal of Vegan Meatballs on a bed of creamy Polenta (made with water or vegetable stock), and a side of Sautéed Broccoli. Finish the meal with a Vegan Chocolate Cake for dessert!
You can also create a French-themed meal, to please herbivores and carnivores alike! I start with vegetarian French onion soup, and then serve this French classic, Coq Au Vin along with Ratatouille, and a loaf of this golden, crusty Fougasse (France’s answer to the Italian focaccia). And to end the meal? Chocolate Profiteroles!
Vegetarian French Onion Soup
Ingredients
- 3 tablespoons olive oil
- 3 tablespoons unsalted butter
- 3 pounds yellow onions thinly sliced
- 1 1/2 teaspoons granulated sugar
- 2 cloves garlic minced
- 1/3 cup dry white wine
- 8 cups low-sodium vegetable broth
- 2 teaspoons balsamic vinegar
- 1 bay leaf
- 1 1/2 teaspoons dried thyme
- Kosher salt and black pepper to taste
- 4 slices of baguette
- 1 cup grated Gruyère cheese
Instructions
- In a large pot, heat oil and butter over medium heat. Add the thinly sliced onions and cook, stirring occasionally, for about 20 minutes.
- Add the sugar and cook another 20 minutes or until the onions are caramelized and golden brown.
- Stir in the minced garlic and cook for 2 minutes. Deglaze the pot by adding the white wine and scraping the bottom of the pot to loosen any browned bits.
- Add the vegetable broth, balsamic vinegar, bay leaf, dried thyme, salt, and pepper. Bring to a simmer and cook for 30 minutes.
- Meanwhile, preheat the oven to 400°F. Place the baguette slices on a baking sheet and toast in the oven for about 8-10 minutes, until crispy and golden. Remove from the oven.
- Adjust the soup seasoning as needed with more salt or balsamic vinegar. Ladle the hot soup into oven-safe bowls. Top each with a slice of toasted baguette and sprinkle generously with grated Gruyère cheese.
- Place under the broiler for 3-4 minutes, or until the cheese is melted and bubbly.
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