This is an overhead image of a white crock filled with french onion soup. On top of the soup is a piece of French bread, melted cheese, and thyme. The crock sits on a white counter with an off-white tea towel to the left side of the image.
This vegetarian French onion soup is the ultimate comfort food! It’s topped with hearty toasted French bread and golden, melty Gruyere cheese.

If I could pick only one soup to eat for the rest of my life, it would be this homemade vegetarian French Onion Soup. Bold statement, I know.

French onion soup is one of my longtime favorites. I first had it at a Jersey diner and I fell in love with the caramelized onions and melty Gruyere. I mean, it basically has all my favorite things wrapped into a cozy, comforting soup.

Traditionally French Onion Soup has a beef broth base. To make it a vegetarian French onion soup, we are swapping in some vegetable broth. Feel free to use whatever your favorite broth is!

Vegetarian French Onion Soup Ingredients:

  • Onions: I used sweet onions or yellow onions.
  • Olive oil
  • Butter
  • Agave Nectar: We’re only using a quick drizzle at the end of the onion caramelization. If you don’t have agave or prefer something else, honey, maple syrup, or your favorite granular sugar is also a good opion!
  • Garlic: mmm garlic why you be so good?
  • Dry red wine: this adds some depth and more flavor to the broth of the soup, but it’s optional. You can just add more broth if you don’t want to use wine.
  • Low sodium vegetable broth: I find broths can be really variable with how much salt they contain. So, I find it best to use low-sodium broth and then add salt to taste.
  • thyme leaves
  • salt
  • ground pepper
  • French bread: If you want to make this recipe gluten free, use your favorite gluten free bread!
  • Gruyere cheese: I mean, this is one of the stars of the show. If you need to sub something else, I think Swiss would be your best option.

How to Caramelize Onions:

The key to perfectly caramelizing onions is very visual. So, stay closeby your pot so you can keep an eye on your onions! Be vigilant and be patient.

First, soften the onions. In a large pot, heat the olive oil over medium high heat. Once hot, add the onions and cook for about 20 minutes until they soften and start to caramelize. 

The visual cue here is the onions will look translucent around the edges and softer than when they were raw.

Then, turn down the heat and cook for longer. Add the butter and continue to cook the onions for 15 – 20 more minutes until the onions reduce and brown.

The visual cue here is you want them to get smaller. Turn down the heat if the onions start to burn, you want them to slowly cook and get golden brown. 

Cook slow and low until they darken. Cook even longer until they Stir in the agave nectar and garlic and continue to cook until the onions are darker brown, another 10 minutes.

This is an overhead image of a white crock filled with french onion soup. On top of the soup is a piece of French bread, melted cheese, and thyme. The crock sits on a white counter with an off-white tea towel to the left side of the image.

How to make Vegetarian Onion Soup:

After you’re done caramelizing your onions (directions above!)

Deglaze. Stir in the red wine. Use a wooden spoon to scrape the bottom of the pot to deglaze the pot. 

Add the vegetable broth, thyme leaves, salt and pepper to the pot. 

Simmer. Bring the mixture to a simmer and cook for 20 minutes, stirring every few minutes. 

Toast your bread. Brush your bread with butter or oil and toast for 10 minutes on a baking sheet. After 5 minutes, flip the toast halfway and continue to toast until both sides are golden brown.

Prep the soup bowls. Divide the soup between four oven-proof bowls. Place the toasted piece of bread in each soup bowl. 

Top with cheese. Divide the shredded cheese on top of the four soups. 

Broil. Place the bowls on a large rimmed baking sheet and broil until the cheese is melted, golden brown and bubbly. 

How to make this gluten free?

It’s simple! All the ingredients are naturally gluten free except the bread. So, use your favorite gluten free bread to toast and top your soup. Simple as that!

How to make vegan french onion soup:

There are only two ingredients in this recipe you need to swap if you’re looking to make it vegan. First, the butter. Simply use vegan butter or you can just add more olive oil and skip the butter thing altogether.

Second, the Gruyere cheese. You can skip the melty cheese on top, or use your your favorite melt-able vegan cheese.

I’m always amazed at the vegan and dairy free cheese options I see in food stores lately. They melt, they stretch, the broil. So if you want that iconic cheese melt on top of your French onion soup, sub in your favorite vegan cheese!

This is a side image of four white crocks filled with french onion soup. The soup is topped with French bread and Gruyere cheese and a thyme sprig. The crocks sit on a white counter and an ivory tea towel is weaved in between the crocks.

More Vegetarian Soups to Try:

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This is an overhead image of a white crock filled with french onion soup. On top of the soup is a piece of French bread, melted cheese, and thyme. The crock sits on a white counter with an off-white tea towel to the left side of the image.

Vegetarian French Onion Soup

  • Author: Lindsay Grimes Freedman
  • Prep Time: 15 min
  • Cook Time: 50 min
  • Total Time: 1 hour 5 min
  • Yield: 4 servings 1x
  • Category: appetizer
  • Method: stovetop
  • Cuisine: soup
  • Diet: Vegetarian
Save Recipe

Description

This vegetarian French onion soup is the ultimate comfort food! It’s topped with hearty toasted French bread and golden, melty Gruyere cheese.


Scale

Ingredients

  • 1 ½ lbs onions, peels and sliced into half moons
  • 2 tablespoons olive oil

  • 2 tablespoons butter

  • 1 tablespoon agave nectar (honey or maple syrup works)

  • 3 cloves garlic, minced

  • ¼ cup dry red wine

  • 3 cups low sodium vegetable broth

  • 4 sprigs fresh thyme leaves

  • ½ teaspoon salt

  • ¼ teaspoon ground pepper

  • 4 slices French bread, cut into thick slices

  • 1 cup gruyere cheese, freshly shredded


Instructions


Notes

Photography by Sasha Hooper at Eat Love Eats


Nutrition

  • Serving Size: 1 bowl
  • Calories: 425
  • Sugar: 13g
  • Sodium: 931mg
  • Fat: 22.3g
  • Saturated Fat: 9.9g
  • Unsaturated Fat: 0g
  • Trans Fat: 0g
  • Carbohydrates: 42.3g
  • Fiber: 4.5g
  • Protein: 13.9g
  • Cholesterol: 45mg

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