Vegetarian French Onion Soup

Name: Vegetarian French Onion Soup
Prep time: 10 min
Cook time: 75 min
Total time: 85 min
Ingredients: ⅛ cup olive oil; 3 onions (medium, sliced); ½ teaspoon brown sugar; 1 bay leaf; ½ teaspoon salt; 2 cloves garlic (minced); 1 teaspoon dried thyme; 1 teaspoon dried oregano; ¼ cup red wine; 3 tablespoons all-purpose flour; 4 cups low sodium vegetable broth; ¼ teaspoon black pepper (to taste); 1 cup baguette (cut into cubes); 1 cup gruyere cheese (shredded)

By Shruthi B. MakanjuPublished Jul 08, 2024

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Reviews

Prep Time 10

Cook Time 1 15

Total Time 1 25

Servings 6 servings

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This vegetarian French onion soup is rich, hearty, and packed with so much flavor without any meat. It’s made with a delicious combination of caramelized onions, savory broth, and topped with melted cheese. This is my favorite recipe whenever I want a comforting bowl of soup to warm me up on chilly days.

An image of one serving of vegetarian French onion soup in a small bowl.

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💭 Why you’ll love this recipe

Great make-ahead dish. You can caramelize the onions and simmer the soup in advance, and add the cheese and French bread right before serving.
Ultimate comfort food. Having a bowl of this hearty soup is enough to warm you up, especially during the colder months. The rich flavor combinations of caramelized onions, vegetable broth, and herbs make it so satisfying.
Family favorite. This is a classic soup that never fails to impress. If you’ve never made it before, it’s guaranteed to be your family’s new favorite, and it’s always a hit with guests.

📋 Ingredients and notes

To make this vegetarian French onion soup recipe, you’ll need onions, garlic, brown sugar, olive oil, red wine, all-purpose flour, vegetable broth, dried oregano, dried thyme, bay leaf, salt, black pepper, gruyere cheese, and baguette.

An overhead image of the ingredients of vegetarian French onion soup.

Variations & Substitutions

Onions. Yellow onions are traditional, but you can use a mix of yellow, white, and red onions for a more complex flavor.
Garlic. Use fresh garlic for the best flavor, but in a pinch, you can use garlic powder.
Brown sugar. To help caramelize the onions.
Red wine. You can also use extra vegetable broth with a splash of balsamic vinegar for acidity.
All-purpose flour. You can also use a 1:1 gluten-free flour blend or cornstarch for thickening the soup.
Vegetable broth. Make you own vegetable stock or use store-bought vegetable broth. To make the flavor closer to beef broth, you can add a pinch of soy sauce of Worcestershire sauce.
Seasonings. I used dried oregano, dried thyme, bay leaf, salt, and ground black pepper. You can also use fresh herbs.
Gruyere cheese. Swiss cheese and emmental cheese work well, too. To make it vegan, you can use a vegan cheese that melts well or skip the cheese entirely.
Baguette. You can toast the baguette slices for a delicious crunch. If you don’t have a baguette, you can use any crusty bread like ciabatta or sourdough. If you have gluten sensitivities, make sure to use gluten-free bread.

📖 How to make vegetarian French onion soup

Step 1:
Bring a large Dutch oven pot over low heat and add the olive oil once hot. Add the onions, sugar, bay leaf and a pinch of salt. Cook, stirring occasionally for 30 to 45 minutes to caramelize.

An overhead image of onions, brown sugar, and bay leaf in a dutch oven.

Step 2:
Add the garlic, thyme, oregano and cook for another minute.

An overhead image of adding dried herbs and seasonings to the pot.

Step 3:
Pour the wine and turn the heat to medium. Simmer until wine evaporates, about 2 minutes. Reduce the heat to low, add the flour and cook for 1 minute stirring frequently.

An overhead image of adding red wine to the caramelized onion mixture.

An overhead image of adding flour to the soup mixture.

Step 4:
Add the vegetable broth, salt, pepper and simmer, uncovered, on low for 10 minutes. Stir occasionally to avoid sticking to the bottom of the pan. Remove the bay leaf.

An overhead image of adding vegetable broth, salt, and pepper to the soup mixture.

Step 5:
Preheat a broiler on high or an oven at 430º F. When the soup is ready, pour it carefully into an oven-safe bowl. Add the cubes of baguette to the soup and the cheese on top of the bread.

An overhead image of adding baguette to a bowl of French onion soup.

An overhead image of adding cheese to the baguette slices over the soup.

Step 6:
Broil until slightly brown and the cheese is melted. Serve immediately.

An overhead image of vegetarian French onion soup, ready to be served.

Shruthi’s Top Tip

To caramelize perfectly, slice the onions uniformly, don’t skip the salt at the beginning to draw out moisture and stir the onions occasionally to avoid burning and ensure they cook evenly!

Use a heavy-bottomed Dutch oven to maintain steady heat distribution.
Let the red wine reduce completely to enhance the depth of flavor without overpowering the soup.
Sprinkle the flour gradually while stirring to avoid lumps and ensure a smooth consistency.
Simmer the soup uncovered to allow it to reduce slightly and intensify the flavors.

👩🏽‍🍳 Troubleshooting FAQs

What if I don’t have red wine?

You can substitute with a splash of balsamic vinegar or extra vegetable broth to maintain the flavor balance.

How can I avoid burning the onions?

Cook them on low heat and stir occasionally, making sure they turn a deep golden brown without blackening.

Why is my soup too thin?

Simmer the soup uncovered a bit longer to reduce and thicken it.

How do I get the cheese perfectly melted?

Use the broiler and keep a close watch, removing the soup as soon as the cheese is bubbly and golden.

🍴 How to serve French onion soup

Serve this vegetarian soup as a starter for weeknight dinners, holiday gatherings, or date nights. I like to pair it with a simple salad like my caesar salad or garlic kale salad. It also goes well with pasta. Try serving it with my pasta fresca, pasta alla norma, or sun-dried tomato pasta.

An image of vegetarian French onion soup in a bowl.

🍴Storage and reheating suggestions

To store leftovers, transfer the soup to an airtight container and refrigerate for 3-4 days. You can also freeze the soup for up to 3 months.

To reheat, transfer the soup to a saucepan and heat over medium heat. Add a splash of water or broth if needed. You’ll want to add the baguette slices and grated cheese just before serving to retain the texture and flavor.