French Onion Soup Recipe

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Rich, sweet, and savory, this vegetarian French Onion Soup is a revelation in a bowl. I’ve unlocked the secret to making the absolute best bowl of onion soup using healthy, homemade veggie stock and the traditional crunchy, cheesy crouton topping, and I can’t wait to share it with you!

french onion soup in two cream colored soup bowls with spoons on a black slate tray. soup garnished with some parsley.

About French Onion Soup

I have received so many requests for this classic French soup over the years. In fact, it is one of the most requested recipes of all time! It’s really no surprise though.

French Onion Soup is one of our comfort foods that has a lovely balance of savory and mild sweet flavors and gorgeous textures. It’s also super cozy and budget-friendly!

This classic soup is made by caramelizing onions in butter, which are then deglazed with dry white wine and further cooked with meat or vegetable stock, then finished with toasted bread or croutons with melted cheese.

I make this vegetarian version of this homemade French Onion Soup recipe with a good and flavorful homemade Vegetable Stock.

The stock is an essential ingredient that can make or break your soup. I suggest using either homemade stock (which is the best option) or a low sodium vegetable broth or stock (which is an acceptable alternative).

The most important technique to get this dish right is caramelizing the onions. While this step isn’t difficult, it’ll take about 40 to 45 minutes depending on the pan thickness and size. Go slow and steady when sautéing the onions to ensure you coax the most marvelous sweet flavor from them.

In this post, I offer two options, that is to broil (grill) or toast bread separately. Most often, I place the toasted bread topped with cheese on the soup and broil it in the oven (broiler method) until the cheese melts.

You can also opt to melt the cheese on the bread toasts separately and then place them on the soup while serving. Choose whatever is easiest for you.

Ingredients & Substitutions

Perhaps surprisingly, this complexly flavored soup has just 10 simple ingredients. Here’s what you’ll need:

  • Onions – Any variety of onions can be added like red, yellow, white onions, vidalia onions, shallots or even leeks. Depending on the type of onions used, the flavors will vary. I prefer this soup with red onions. Just make sure to slice the onions evenly so that they get cooked uniformly.
  • Butter – Add either salted or unsalted butter. Make sure to adjust the seasoning as you go. Vegan butter can also be added, if needed.
  • Dry White Wine – Wine gives a lovely depth of flavor here, but you can sub in apple cider vinegar, white wine vinegar, red wine vinegar, or sherry if needed.
  • Flour – Either whole wheat flour or all-purpose flour can be used. A cup-for-cup all-purpose gluten-free flour blend can also be used, if needed.
  • Bay Leaf – Tej Patta (Indian bay leaf) can also be used.
  • Garlic – Fresh cloves are preferred for a more potent flavor, but you can use ¼ teaspoon of ground garlic powder for each clove if necessary.
  • Vegetable Stock – If possible, I recommend using a flavorful homemade stock. If not, opt for a low-sodium, high-quality store-bought brand.
  • Salt & Freshly Crushed Black Pepper – Simple seasonings yield delicious results.
  • Fresh Rosemary or Thyme – Optional, but recommended for depth of flavor. 1 teaspoon of dried herbs can also be used as an alternative to fresh herbs.
  • Crusty Bread – French bread, baguette, sourdough, or sandwich bread will all work.
  • Gruyere Cheese – Opt for a vegetarian (rennet-free) version of melty cheese. While Gruyere is the classic choice for this French soup, you can swap in Swiss cheese, provolone, fontina, gouda, mozzarella or parmesan as needed. Feel free to use plant-based cheese for a vegan option.
french onion soup in two cream colored soup bowls with spoons on a black slate tray. soup garnished with some parsley.
Step-by-Step Guide

How to make French Onion Soup

Preparation

1. Peel, rinse and thinly slice about 4 medium-sized onions (300 grams) for a total of 3 cups of thinly sliced onions.

Sometimes there are some black spots or marks on the onions and these need to be completely rinsed before slicing the onions.

Finely chop or mince two small to medium-sized garlic cloves and set aside.

Pro Tip: Do onions make you cry? Try freezing them for about 10 to 15 minutes before slicing to inhibit the development of the sulfurous compound that causes eye irritation.

sliced onions on a chopping board.

Caramelize Onions

2. Place a heavy-bottomed pot on the stovetop. Add 3 tablespoons butter and let the butter melt.

butter being melted in a pan.

3. When the butter starts melting, add the sliced onions.

onions added to melted butter.

4. Mix the onions with the butter really well.

onions mixed with the butter.

5. Add a pinch of salt and stir.

a pinch of salt being added to the onions.

6. Stirring often, continue to sauté the onions on a low or medium-low heat.

onions being sautéed.

7. Initially, the onions will soften and become translucent. Continue to stir at intervals of 2 to 3 minutes.

onions have softened.

8. After some minutes the onions will start to become light golden.

onions have turned light golden.

9. The onions need to be cooked more to reach their full caramelized potential. After the onions reach a light golden stage, they have to be stirred continuously so that they are evenly cooked and become a deep golden brown.

onions have caramelized to a deep golden brown.

Deglaze

10. When the onions have caramelized and have a nice golden color to them, add 2 tablespoons dry white wine.

If you do not have white wine, then add ½ to 1 tablespoon apple cider vinegar, white wine vinegar, red wine vinegar, or sherry.

dry white wine being added to the caramelized onions.

11. Deglaze and scrape, remove all the stuck bits of browned onions from the bottom. Sauté for 1 to 2 minutes on a low to medium-low heat.

deglazing with dry white wine.

Add Flour

12. Add 2 tablespoons of whole wheat flour or all-purpose flour.

flour added to the onions.

13. Mix very well and sauté for 2 minutes on a low to medium-low heat.

the onions are sauteed for 2 minutes after flour is added.

14. Add ½ teaspoon finely chopped garlic and 1 bay leaf. Stir and sauté for a minute. If the onions start sticking to the pan, then sprinkle in some water or stock.

garlic and bay leaf are added.

15. Add 3.5 cups of vegetable stock.

vegetable stock is being added to french onion soup.

16. Place 1 sprig of rosemary or thyme on the stock.

a sprig of rosemary placed on the stock.

Simmer French Onion Soup

17. Season with salt to taste. Remember that as the soup simmers, the flavors will become more concentrated, so start with a small amount of salt to begin.

after 30 minutes of simmering, season french onion soup with salt.

18. Add ¼ to ½ teaspoon freshly crushed black pepper. Mix again.

seasoning with crushed black pepper.

19. Cover the pan. Simmer for 30 minutes on a low heat. You can check the soup and give it a quick stir after about 10 to 15 minutes.

pan covered with lid and soup being simmered for 30 minutes.

20. In this below photo, the French Onion Soup is done and ready to be served.

french onion soup is done.

Toast Bread

21. When the soup is simmering, toast the bread. Slice a baguette, french bread or your preferred bread into even ½ inch thick slices.

I have toasted the french bread slices in an oven, but you could toast them in a skillet or a flat griddle.

baguette being sliced.

22. Place the bread slices on a baking tray or a baking sheet. Brush with some melted butter or olive oil.

baguette slices brushed with olive oil and placed on baking tray to make croutons for french onion soup.

23. Preheat the oven for 15 minutes at 230 degrees C/450 degrees F. In a preheated oven, toast the slices. Halfway through remove the tray and turn each slice.

baguette slices being toasted in the oven.

24. Remove and keep aside when the slices become light golden or lightly toasted.

toasted baguette slices.

Option 1: Broiling (Grilling)

25. Now you can use baking safe soup bowls for individual servings or use a baking safe pot or pan.

Keep the soup bowls on a baking tray. Pour the soup in these bowls.

individual serving bowls with french onion soup in them.

26. Place toasted bread slices on the onion soup.

If you have used a Dutch oven for making the soup, then you can place the croutons or toasted bread slices directly in it.

toasted baguette slices being placed on the soup.

27. Sprinkle grated vegetarian gruyere cheese all over the toasted bread slices.

baguette slices topped with grated gruyere cheese to make french onion soup.

28. Place the bowls on a baking tray, then broil in the already preheated oven at 230 degrees C/450 degrees F till the cheese melts.

(Broiling means placing the pan or tray beneath the top heating element of the oven.)

soup bowls placed in the oven to broil.

29. Let the cheese melt or become golden. Remove and serve hot. You can garnish with some chives or parsley while serving.

french onion soup bowls removed from the oven with the cheese melted and golden.

Option 2: Baking Cheese Toasts Separately

30. For baking the cheese toasts separately
, sprinkle grated gruyere cheese (vegetarian) on the toasted bread slices.

toasted baguette slices with grated gruyere cheese on them.

31. Bake at 230 degrees C/450 degrees F in a preheated oven till the cheese melts. Keep the tray near the top heating element so that the cheese melts quickly.

cheesy baguette slices in the oven.

32. Bake until the cheese melts.

baguette slices with cheese melted on top.

33. Pour steaming hot French Onion Soup in soup bowls. Place the cheese toasts on the onion soup. Garnish with some parsley or chives while serving.

Serve hot French Onion Soup as a starter or as a light dinner meal. You can also pair it with a hearty flavorful salad of your choice.

french onion soup in a cream soup bowl with red handles with toasted baguette slices with melted cheese on top.

Expert Tips

  1. Herbs: You can skip adding fresh herbs like rosemary or parsley if you don’t have them. Fresh thyme can also be added instead of rosemary.
  2. Vegetable Stock: Avoid using packaged stock having a high sodium content. It is better to make vegetable stock and use it in the recipe.
  3. Flour: You can use either whole wheat flour or all-purpose flour. Gluten-free flour is also an alternative.
  4. Caramelizing Onions: For a truly authentic French onion flavor, it is important to caramelize the onions really well. So, use a heavy pan or pot, keep it on a low or low-medium heat, and stir often when sautéing the onions. Toward the end stage when the onions become light golden, you have to stir often so that the onions get an even golden color and do not burn or darken. Even a slight burning of the onions will ruin the entire batch.
  5. Wine: Sherry wine, dry white wine or red wine can be used. If you do not plan to add wine, then use ½ to 1 tablespoon of either of these vinegars – white wine vinegar, red wine vinegar or apple cider vinegar.
  6. Gluten-Free Option: For the bread, use a gluten-free bread like a rice flour bread and swap in a gluten-free flour blend to help thicken the soup.

FAQs

Why does the French Onion Soup taste bitter?

Oops! sounds like you made the mistake of cooking the onions too hot too fast. Make sure you use a heavy-bottomed pot to prevent scorching, keep the onions on a low to medium-low heat, and stir often. Don’t rush! The whole process will take about 40 to 45 minutes if you do it properly.

Pro Tip: Make an extra large batch of caramelized onions, then freeze the extras for later. They’re delightful flavor bombs that can be used in a multitude of recipes, and they’ll keep well in the freezer for up to 1 month!

Can I make vegan French Onion Soup?

Sure! Just opt for either EVOO or plant-based butter. Also, use vegan cheese.

Can I make gluten-free French Onion Soup?

Sure! Just use gluten-free bread and gluten-free flour.

What is the best way to process onions for French Onion Soup?

I like to remove the root and stem ends, slice the onions in half vertically (from pole to pole), then make thin vertical slices on each half.

More Soup Recipes To Try!

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closeup image of french onion soup in a cream colored soup bowl, garnished with some parsley.

French Onion Soup Recipe

Our favorite and classic French Onion Soup recipe made vegetarian. Rich, sweet, and savory, this French Onion Soup is a revelation in a bowl. I've unlocked the secret to making the absolute best bowl of onion soup using healthy, homemade veggie stock and the traditional crunchy, cheesy crouton topping.
5 from 19 votes
Prep Time 5 minutes
Cook Time 1 hour 15 minutes
Total Time 1 hour 20 minutes
Cuisine French, World
Course Appetizers, Starters
Diet Vegetarian
Difficulty Level Moderate
Servings 3
Units

Ingredients

  • 3 cups onions – thinly sliced, or 300 grams, or 4 medium-sized onions
  • 3 tablespoons Butter – can use either salted or unsalted butter
  • 2 tablespoons dry white wine or ½ to 1 tablespoon apple cider vinegar
  • 2 tablespoons whole wheat flour or all-purpose flour
  • 1 bay leaf – or swap with tejpatta (Indian bay leaf)
  • ½ teaspoon garlic – finely chopped, or 2 small to medium garlic cloves, finely chopped or minced
  • 3.5 cups Vegetable Stock – preferably a flavorful homemade stock or broth
  • salt as required – optional
  • ¼ to ½ teaspoon black pepper – freshly crushed
  • 1 sprig rosemary or thyme, optional
  • ½ loaf of French Bread or baguette or sandwich bread
  • 6 tablespoons gruyere cheese – grated, (vegetarian) or add as required
  • 1 tablespoon chopped parsley or chives for garnish, optional

Instructions
 

Preparation

  • Peel, rinse and slice the onions thinly and evenly. Finely chop or mince two garlic cloves and set them aside.

Cooking onions

  • Place a heavy pan on the stovetop. Add butter.
  • When butter states melting, add the sliced onions with a pinch of salt.
  • Mix the onions with the butter really well.
  • Stirring often continue to sauté the onions on a low or medium-low heat until the onions caramelize.
  • Initially stir the onions after an interval of 2 to 3 minutes till they become light golden. When the onions turn light golden, then stir the onions continuously for even cooking and browning.

Deglazing

  • Once the onions have caramelized and have a nice golden color to them, add 2 tablespoons dry white wine.
  • Deglaze and remove all the stuck bits of caramelized onions from the bottom of the pan. Sauté for 1 to 2 minutes.

Adding flour

  • Now add the flour.
 Mix thoroughly and sauté for 2 minutes.
  • Next add the garlic and bay leaf. Mix again and sauté for a minute.
    If the onions start sticking to the pan, then sprinkle some water or stock.
  • Add vegetable stock and the rosemary sprig. Additionally, season with salt and freshly crushed black pepper. Stir and mix.
  • I have added salt, as the homemade vegetable stock I had made, did not have any salt in it. But if use stock with salt in it, then you can skip adding salt or add less of it.

Cooking soup

  • Cover the pan with its lid. Simmer for 30 minutes on a low heat.
  • You can check the soup while it is simmering after an interval of 10 to 15 minutes. 

Toasting Bread or Baguette slices

  • When the soup is simmering, toast the slices of french bread or baguette or regular wheat bread or white bread.
  • Slice the french bread or your preferred bread into slices with ½ inch thickness.
  • Place the baguette slices on a baking tray. Brush with some melted butter or olive oil.
  • In a preheated oven toast bread slices at 230 degrees Celsius (450 degrees Fahrenheit) until light golden.

Broiling (Grilling)

  • Place the empty bowls (baking safe and oven heat proof) in a baking tray for individual servings.
    You can also opt to use a baking safe pot or pan like the Dutch oven.
  • Pour the prepared onion soup in the soup bowls.
  • Place toasted bread slices on the onion soup.
  • Sprinkle grated gruyere cheese all over the toasted bread slices.
  • Keep the tray with the soup bowls in a preheated oven and broil at 230 degrees Celsius (450 degrees Fahrenheit) until the cheese melts.
    Broiling means keeping the pan or tray beneath the top heating element of the oven.
  • Let cheese melt or become golden. Remove the tray using oven mitts. Carefully remove the soup bowls using oven mitts or oven gloves from the tray.
  • Serve French Onion Soup, hot garnished with some parsley or chives.

Baking Cheese Toasts Separately

  • For baking the cheese toasts separately, top grated gruyere cheese on the toasted baguette slices.
  • Bake at 230 degrees Celsius (450 degrees Fahrenheit) in a preheated oven until the cheese melts.
  • Pour the steaming hot soup in soup mugs or bowls.
  • Place the cheese toasts on the soup and serve straightaway.
  • Garnish with some parsley or chives while serving.

Notes

  • Herbs: Herbs like rosemary or parsley can be skipped completely. Fresh thyme can also be added instead of rosemary. 
  • Onions: Slice the onions thinly and evenly. You can use any variety of onions like red onions, white onions, yellow onions, vidalia onions or shallots. 
  • Vegetable stock: Avoid using packaged stock having a high sodium content. It is better to make vegetable stock and use it in the recipe. 
  • Flour: You can either whole wheat flour or all-purpose flour. 
  • On caramelizing onions: For the soup to have a truly authentic and great flavor, it is important to caramelize the onions really well. So use a heavy pan or pot. Stir often when sauteing the onions. Toward the end stage when the onions become light golden, you have to stir often so that the onions get an even golden color and do not burn or darken. So stirring and cooking onions on a low to medium-low heat is the key. Even a slight burning of the onions will ruin the entire soup. 
  • Wine: You can use sherry wine or dry white wine. You can even use red wine. If you do not plan to add wine, then use vinegar. I suggest ½ to 1 tablespoon (depending on your taste) of white wine vinegar, red wine vinegar or apple cider vinegar. 
  • Gluten-free option: For the bread, use a gluten-free bread.
  • Cheese: Apart from Gruyere cheese, you can also add a vegetarian Parmesan cheese. Other options you can consider are Swiss cheese, provolone, fontina, gouda or mozzarella.
  • Vegan option: Replace with a vegan butter or olive oil or neutral flavored oil and vegan cheese. 

Nutrition Info (Approximate Values)

Nutrition Facts
French Onion Soup Recipe
Amount Per Serving
Calories 519 Calories from Fat 198
% Daily Value*
Fat 22g34%
Saturated Fat 13g81%
Cholesterol 63mg21%
Sodium 1645mg72%
Potassium 360mg10%
Carbohydrates 60g20%
Fiber 5g21%
Sugar 11g12%
Protein 19g38%
Vitamin A 1214IU24%
Vitamin B1 (Thiamine) 1mg67%
Vitamin B2 (Riboflavin) 1mg59%
Vitamin B3 (Niacin) 4mg20%
Vitamin B6 1mg50%
Vitamin B12 1µg17%
Vitamin C 12mg15%
Vitamin D 1µg7%
Vitamin E 1mg7%
Vitamin K 4µg4%
Calcium 368mg37%
Vitamin B9 (Folate) 134µg34%
Iron 3mg17%
Magnesium 52mg13%
Phosphorus 321mg32%
Zinc 2mg13%
* Percent Daily Values are based on a 2000 calorie diet.

This French Onion Soup recipe from the archives was first published on October 2020. It has been updated and republished on February 2024.

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Welcome to Dassana's Veg Recipes. I share vegetarian recipes from India & around the World. Having been cooking for decades and with a professional background in cooking & baking, I help you to make your cooking journey easier with my tried and tested recipes showcased with step by step photos & plenty of tips & suggestions.

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