Vegetarian French Onion Soup

Lauren Caris Short

By Lauren Caris Short


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5 from 4 votes

Indulge in the deliciousness of Vegetarian French Onion Soup! This recipe puts a vegetarian twist on the classic, using a combination of red and white onions for a bold flavor. It’s an easy-to-follow recipe that won’t disappoint. 

Two bowls of Vegetarian French Onion soup topped with bread and cheese on a white table sprinkled with herbs.

French Onion soup is the ultimate comfort food. It’s rich, bold in flavor and covered in cheese. Who says the Vegetarian version can’t be as good? In this recipe, I’m going to show you how to make a vegetarian French onion soup that won’t disappoint your cravings!

I have distinct memories of traveling in France as a child and ALWAYS eating French onion soup while I was there. Traditionally made with beef broth, this soup has a tremendously hearty base, which when added to the sweet caramelized onions, creates a comfort food that is just to die for. I have never successfully found a vegetarian version that lived up to the original.

Until now.

Close up of two bowls of Vegetarian French Onion soup topped with bread and cheese on a white table.

The trick to French Onion soup is the technique. It cannot be rushed; that would cause browning of the onions and not caramelization. The low, slow cooking of the onions allows their sugars to break down and create a mound of sweet, earthy goodness that will form the base of this soup. If you rush this step, you really might as well not bother. Yes, it takes around 3 hours to make this soup… but is it worth it? Oh yes.

Caramelized red and white onions in a black frying pan.

I used my homemade vegetable stock for this soup rather than a store-bought one. Homemade stock is another element that will elevate your soup to a different level. It’s something that’s so easy to make with any vegetables you have on hand, and it is extremely forgiving. You can give or take the amount of water you use depending on how concentrated you want your stock to be.

If you are going to use store-bought vegetable stock for this recipe, I recommend using a low-sodium version. You can season the soup with salt and pepper to taste, but it’s difficult to take away too much salt if the stock you are using is already quite salty.

Spoonful of French Onion Soup with onions on it being held above a bowl of French Onion Soup in a white bowl topped with bread and cheese.

The crowning glory of any French onion soup is its crouton and Gruyere cheese hat. I certainly wouldn’t want to be the one who risks serving someone this soup without the signature cheese hat! And don’t go skimping on the cheese! Any excess cheese will fall and melt into the soup during its heat in the oven, making a delightful surprise as you reach the bottom of your bowl!

If you make this when you have some friends around for dinner, they will NOT be disappointed in this soup. This vegetarian version packs just as much punch as the original. Give it a try!

Vegetarian French Onion soup in a white bowl on a white table with herbs on the table and another bowl of soup in the background.
Print Recipe
5 from 4 votes

Vegetarian French Onion Soup

Indulge in the deliciousness of Vegetarian French Onion Soup! This recipe puts a vegetarian twist on the classic, using a combination of red and white onions for a bold flavor. It's an easy-to-follow recipe that won't disappoint. 
Prep Time1 hour
Cook Time1 hour 20 minutes
Total Time2 hours 20 minutes
Course: Soup
Cuisine: French
Diet: Vegetarian
Keyword: Vegetarian French Onion Soup
Servings: 4 people
Calories: 296kcal


  • 3 white onions large
  • 3 red onions large
  • 2 tbsp butter
  • 4 tbsp olive oil
  • 1 tsp sugar
  • 1/2 tsp salt
  • 2 cloves garlic minced
  • 1/2 cup white wine dry
  • 8 cups vegetable stock low sodium
  • 2 bay leaves
  • 4-6 sprigs thyme fresh
  • 1/2 tsp black pepper
  • french bread sliced, for topping
  • swiss gruyere cheese for topping


  • Peel and slice the onions in half lengthways. Place each half flat side down and cut into strips about 1/4 wide. They will look like little semi circles as they fall apart.
  • Heat the butter and olive oil on a medium/low heat until the butter is completely melted. Add the onion, stir to coat then cover and let cook for 10 minutes. The heat should be low enough that the onions do not brown but just begin to get soft. After the first 10 minutes, increase the heat to medium, add the sugar and stir the onions once every 10 minutes. Do not cover the onions for this. Repeat stirring every 10 minutes until 1 hour has passed and the onions are brown and caramelized. The magic will start to happen around 45-50 minutes.
  • Add the minced garlic, white wine, salt and pepper to the onions and let cook for a couple of minutes. Then add the vegetable stock, thyme and bay leaves, reduce the heat to low and let simmer for 1 hour.
  • Preheat the oven to 350 degrees Farenheit. (175 degrees Celsius) Spoon the soup into bowls, top with a slice of french bread and then generously cover the entire dish with Gruyere cheese. Bake in the oven for 20 minutes before switching it to grill (broil) for the last couple of minutes to let the cheese turn golden brown.
  • Serve immediately.


Notes: If you want to make the soup and serve it later, stop at the end of step 3 and store the soup in an airtight container in the fridge for up to 5 days. When ready to serve, spoon the into bowls and go from step 4.


Calories: 296kcal | Carbohydrates: 24g | Protein: 2g | Fat: 20g | Saturated Fat: 6g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 12g | Trans Fat: 0.2g | Cholesterol: 15mg | Sodium: 2224mg | Potassium: 280mg | Fiber: 3g | Sugar: 12g | Vitamin A: 1231IU | Vitamin C: 14mg | Calcium: 51mg | Iron: 1mg

Images by Lauren Caris Short.

Images by Lauren Caris Short.

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  5. One of my favs. This looks so good that melty gruyere and super flavourful soft onions yum I have minnestrone soup on the hob but kinda wishing it was french onion.

    • Awww thanks Liyana!! You should definitely try it… it was ULTIMATE comfort! Need to make it myself again REALLY soon…