French Lentil Soup

This French Lentil Soup recipe has all of the flavors we love about French onion soup with the added green lentils. Our lentil French onion soup is a delicious mix of caramelized onions, Parmesan cheese, green lentils and butter. 

If you’re like me and love to make homemade soup during the cold winter months, I know you’ll enjoy this French Lentil Soup recipe as much as I do!

This vegetarian French Lentil Soup is loaded with flavor and it is so simple to make any night of the week!

Best French Lentil Soup Recipe Ingredients

We use many of the same ingredients that you’d use to make a French onion soup with, and then we add green lentils to the mix.

• Lentils. Use green lentils for this soup because they tend to hold their shape during the cooking process. If you can’t find green lentils, you can use brown lentils instead.
• Aromatics. We use a combination of sweet onion, red onion, and garlic for this soup.
• Seasoning. This soup is seasoned with fresh thyme and dried bay leaves.
• Butter. We use a combination of butter and extra-virgin olive oil to saute the onion with.
• Broth. You can use either chicken broth or vegetable broth for this soup.
• Worchestershire sauce. A little Worchestershire sauce adds flavor to this soup. 
• Cheese Toasties. We garnish this soup with cheese toasties made with French bread, olive oil and Parmesan cheese.

Find the printable recipe with measurements below.

Variations

• Wine. Add 1/2 cup sherry or wine (red or white) to deglaze the onions with.
• Cheese. Garnish with Gruyere cheese instead of Parmesan.

How to Make French Lentil Soup

1. Caramelize Onions.  Melt butter in a large soup pot or Dutch oven over medium low heat.  Add onions, sprinkle with a pinch of salt, and cook for 40 minutes until onions are soft and caramelized. Add garlic the last 2-3 minutes of cooking.
2. Add Lentils, Broth and Herbs. Pour in broth, lentils, bay leaf and sprigs of thyme and parsley.
3. Simmer.  Bring to a boil, then place lid on pot and reduce heat to a low simmer for 40-45 minutes until lentils are tender.
4. Make Toasties. Arrange baguette slices brushed with olive oil on a baking sheet in a single layer. Bake for 1-2 minutes then remove from oven and sprinkle with grated Parmesan cheese and bake another 2-3 minutes until melted.
5. Serve. Ladle soup in bowls and float 2-3 Parmesan toasties on top.

What Are The Best Onions For Lentil French Onion Soup?

The best onions to use for lentil French onion soup are yellow onion, sweet onion (such as Vidalia and Walla Walla) and red onion.

• Yellow onion. Yellow onions are probably the most commonly used onion.  They’re great grilled or simmered in soups and stews.
• Sweet onions.  Sweet onions (Vidalia and Walla Walla) have a little less of a bite to them than the yellow or white onion, and they taste a little on the sweet side.
• Red onions. Red onions are similar in flavor to the rustic yellow onion.  

How To Caramelize Onions

This is probably the most important part of a good onion soup. Caramelizing 3-4 onions can typically take up to an hour, but we cut down on time just a bit for this soup and we caramelize the onions for about 40 minutes.

1. Slice onions. Trim the tip and root from onions.  Cut the onions in half and remove the skins.  Cut each half into thin slices.
2. Heat butter. Melt butter in large skillet over medium low heat. Or if using olive oil, heat oil over medium low heat.
3. Add sliced onions. Add all of the sliced onions to the pan and stir them to coat with melted butter or olive oil.
4. Cook. Cook the onions and check every 5-7 minutes. As the onions cook, stir and scrape any onion glaze (fond) that forms at the bottom of the pan. As the onions start to soften, there will be liquid in the pan. After about 20 minutes, the onions will turn blonde and become sticky and you’ll see some of the glaze (fond) building up at the bottom of the pan. Towards the end of the process, the onions will turn a darker brown color and release a delicious aroma.

Tips For Caramelizing Onions

• The best pans for caramelizing onions is a good stainless steel or cast iron skillet.  You can use a non-stick pan, but the onions just don’t caramelize quite as nicely.
• Caramelizing onions is a process that breaks down the sugars in the onions giving the onions a deep rich flavor. It’s really as simple as melting some butter (you can also use vegan butter or olive oil) and adding the thinly sliced onions to the pan along with a pinch of salt.
• Don’t over-crowd the pan.  Depending on the size of your pan, it’s best to caramelize 3-4 onions at a time.
• Cook the onions slowly on low heat until they turn a rich mahogany brown in color.
• Once the onions start to cook, be sure to check on them every 5 – 7 minutes to stir them.  Scrape the sticky glaze (fond) that builds up on the bottom of the pan and stir it into the onions.  Lots of flavor in the fond!
• The onions will start to dry at the end of the caramelization process. You can deglaze the pan with either water, broth, sherry or wine.

What Cheese Goes With Lentil French Onion Soup?

Classic onion soup is traditionally topped with crusty bread and sliced or shredded Gruyere cheese.  I’ve kept things simple (and lower in calories and fat) by garnishing this soup with Parmesan cheese, but feel free to go with Gruyere cheese or no cheese at all if you like.

What Are the Best Lentils to Use?

There’s a variety of different types of lentils to cook with, such as green lentils (also called French lentils or Le Puy lentils), red lentils, black lentils (also called beluga lentils) and brown lentils.  I find that Le Puy lentils (also called French Green Lentils) or just plain green lentils and brown lentils are the best lentils to use when making this French lentil soup with because they tend to hold their shape better and retain a slightly firmer texture.  They take about 40 minutes to cook cook. 

Serving Suggestions

This French Lentil Soup is substantially filling on its own, but you could easily serve it with warm crusty bread, a light salad or as a starter soup.

• Romaine Salad
• Chef Salad
• Broccoli Salad Recipe

Looking for More Lentil Soup Recipes to Make?

• Sausage Lentil Soup
• Lentil Rice Soup
• Lentil Vegetable Soup
• Mexican Lentil Soup
• Vegan Lentil Soup
• Italian Lentil Soup
• Red Lentil Soup
• Vegan Mulligatawny Soup

Continue to Content

Print

Yield: 8 servings

French Lentil Soup

Prep Time 15 minutes

Cook Time 1 hour

Total Time 1 hour 15 minutes

Vegetarian French onion soup meets lentil soup with this delicious French Lentil Soup recipe.  This is the best lentil soup with all the flavors we love about French onion soup with added green lentils (or brown lentils) for a more substantially filling and protein rich vegetarian soup. 

Ingredients

• 2 tablespoons extra-virgin olive oil
• 1 tablespoon butter
• 4 cups onion, thinly sliced (about 2 sweet onions and 2 red onions)
• 1-2 garlic cloves, peeled and minced
• 1-2 tablespoons Worcestershire (optional)
• 12 cups vegetable or chicken broth
• 1 cup dried green lentils
• 1 bay leaf
• 1 sprig fresh thyme
• 2-3 sprigs parsley
• 1/2 cup parsley, finely chopped

Cheese Toasties

• Baguette slices
• Olive oil
• Parmesan cheese or Gruyere cheese

Instructions

1. Heat olive oil and butter in a large soup pot or Dutch oven over medium low heat.
2. Add onions, sprinkle with a pinch of salt, and cook for 20 minutes until onions are soft and caramelized. Stir in and saute the minced garlic the last 2 minutes of cooking onions.
3. Stir in 1-2 tablespoons Worcestershire sauce to the onions.
4. Pour in broth, lentils, bay leaf and sprigs of thyme and parsley.
5. Bring to a boil, then place lid on pot and reduce heat to a low simmer.
6. Simmer for 40-45 minutes or until the lentils are tender.
7. Remove bay leaf and thyme and parsley.
8. Ladle soup in bowls and float 2-3 Parmesan toasties on top.
9. You can also ladle soup into bowls, top each with 2-3 slices of bread and top with cheese. Put soup bowls into the oven to melt cheese and toast baguette.
10. Garnish with chopped parsley.

For the Cheese Toasties

1. Arrange baguette slices brushed with olive oil on a baking sheet in a single layer. Bake for 1-2 minutes then remove from oven and sprinkle with grated Parmesan cheese and bake another 2-3 minutes until melted.

Notes

Variations

• Pour in 1/2 cup sherry to deglaze the onions
• Garnish with Gruyere cheese instead of Parmesan

How To Caramelize Onions

This is probably the most important part of a good onion soup. Caramelizing 3-4 onions can typically take up to an hour, but we cut down on time just a bit for this soup and we caramelize the onions for about 40 minutes.

1. Slice onions. Trim the tip and root from onions.  Cut the onions in half and remove the skins.  Cut each half into thin slices.
2. Heat butter. Melt butter in large skillet over medium low heat. Or if using olive oil, heat oil over medium low heat.
3. Add sliced onions. Add all of the sliced onions to the pan and stir them to coat with melted butter or olive oil.
4. Cook. Cook the onions and check every 5-7 minutes. As the onions cook, stir and scrape any onion glaze (fond) that forms at the bottom of the pan. As the onions start to soften, there will be liquid in the pan. After about 20 minutes, the onions will turn blonde and become sticky and you'll see some of the glaze (fond) building up at the bottom of the pan. Towards the end of the process, the onions will turn a darker brown color and release a delicious aroma.

Tips For Caramelizing Onions

1. The best pans for caramelizing onions is a good stainless steel or cast iron skillet.  You can use a non-stick pan, but the onions just don't caramelize quite as nicely.
2. Caramelizing onions is a process that breaks down the sugars in the onions giving the onions a deep rich flavor. It's really as simple as melting some butter (you can also use vegan butter or olive oil) and adding the thinly sliced onions to the pan along with a pinch of salt.
3. Don't over-crowd the pan.  Depending on the size of your pan, it's best to caramelize 3-4 onions at a time.
4. Cook the onions slowly on low heat until they turn a rich mahogany brown in color.
5. Once the onions start to cook, be sure to check on them every 5 - 7 minutes to stir them.  Scrape the sticky glaze (fond) that builds up on the bottom of the pan and stir it into the onions.  Lots of flavor in the fond!
6. The onions will start to dry at the end of the caramelization process. You can deglaze the pan with either water, broth, sherry or wine.

Nutrition Information:

Yield:

8

Serving Size:

1
Amount Per Serving: Calories: 411Total Fat: 12gSaturated Fat: 4gTrans Fat: 0gUnsaturated Fat: 7gCholesterol: 20mgSodium: 447mgCarbohydrates: 60gFiber: 16gSugar: 15gProtein: 17g

theharvestkitchen.com attempts to provide accurate information, however, this nutritional information is provided as a courtesy and is an estimate only. The nutritional information provided comes from online sources and calculations.