Keto French Onion Soup

Keto French Onion Soup is a low-carb version of the traditional classic French onion soup recipe.

Sweet caramelized onion simmered into a beef broth with cheesy keto bread croutons topped with Swiss cheese.

Is French Onion Soup Keto-Friendly?

If you wonder, is French onion soup keto-friendly? Well, no! A traditional French onion soup is not keto-approved.

Below I listed all the ingredients and reasons why you shouldn’t eat a traditional French onion soup on keto:

• Sugar. a classic French onion soup requires onions that are caramelized in sugar. Sugar is your worst enemy on keto since it is pure carbs. Only 10 grams is 10 grams of net carbs!
• White wheat flour. this is used to help thicken the soup, and like sugar, flour is pure carbs, so not for you on keto!
• White wine. White wine is used to deglaze the onions. You can have some dry white wine on keto if used in moderation, but unfortunately, the classic French onion soup uses quite a good amount, which brings the carbs very high.
• Croutons. A classic French onion soup is always topped with lots of toasted French bread. Again, regular bread is not keto-friendly as it is made with wheat flour, high in carbs.

So, as you can see, you can’t eat a classic onion soup recipe.

But let me show you how French onion soup and keto can work together!

How To Make Keto French Onion Soup

There are a few necessary tweaks to make an onion soup keto-friendly.

Let me show you how to select the ingredients to make a keto low-carb French onion soup.

Soup Ingredients

• White onion. Onions are naturally high in carbs, so I use fewer onions in my keto version of the French onion soup. Still, a good enough amount to bring texture and flavor. Don’t use red onions. They are higher in carbs, and the soup would be very sweet.
• Erythritol. It’s the swap to sugar, and it is a 100% keto-friendly keto sweetener that can caramelize onion just as well without adding any carbs.
• Beef bone broth. Also known as keto beef stock sometimes, it’s 100% keto-friendly, so you are safe here. If you want to make a vegetarian French onion soup, swap beef bone broth for vegetable broth.
• Xanthan gum. This is your thickening agent. It contains barely any carbs and replaces high-carb flour found in the traditional French recipe.
• White wine. Not all white wines are keto-friendly. You must use dry white wine like Sauvignon blanc. I also reduced the amount in this recipe to keep the net carbs per serving under control while having the tangy wine flavor.
• Bay leaves. The secret French herb to any good French onion soup and many French dishes.
• Thyme
• Salt. Optional if your beef broth is already high in salt.

Preparing The Soup Broth

It is super easy to make an onion soup. First, heat the butter, add finely sliced white onion, and cook for 20-25 minutes until soft, brown, and fragrant.

Then, add erythritol and salt to caramelize the onion. Finally, deglaze the onions with dry white wine and beef broth.

Choosing The Croutons

The best part of French onion soup is these crunchy croutons and broiled bubbly cheese on top!

You don’t want to miss this even on keto so let me share my tricks to making quick keto croutons to add on top of your soup.

A traditional French onion soup is not topped with small bread croutons but with a thin French baguette slice.

French people eat baguettes daily, and the slice of baguette on top of the onion soup is most of the time a stale baguette that has hardened on the kitchen countertop.

Then, we slice thin pieces of hard baguette and toast it in a bread toaster or oven to get it very hard and crispy.

Finally, we spread fresh butter on the bread and rub a fresh garlic glove to flavor it.

This is then added on top of the onion soup and grated cheese: usually Emmental, Gruyere, or Swiss cheese, and broil in the oven.

Making Keto Croutons

Of course, you can’t eat regular French bread or croutons on a keto diet. But I have a few solutions for you to mimic crispy croutons into your soup.

Make A Quick Keto Microwave Bread

My favorite option is to make my 90-second keto microwave bread recipe in a tall cylinder coffee mug. This keto recipe mimics the baguette shape.

Then, release the bread cylinder and slice it into thin bread slices. The slices will be very soft so bring them into a bread toaster on high until crispy.

Then, spread butter on the toasted bread slices and rub fresh garlic on the bread – onions and garlic are delicious, don’t skip! 

Finally, top your keto onion soup bowl with a slice of this keto crouton recipe, add cheese and broil!

Et voila! You made a keto French onion soup.

If someone asks you if you can eat French onion soup on a keto diet, you can proudly answer yes, and serve this yummy recipe!  

Using store-bought crouton alternatives

If you don’t feel like baking, use some of the options below to mimic croutons into your keto soup:

• Pork rinds: that’s the closest alternative to croutons, and it contains zero carbs, so it’s a great addition to your keto meal.  
• Toasted seeds: like sunflower or pumpkin seeds.
• Parmesan crisp

Storing French Onion Soup

Onion soup stores very well in the fridge for up to 5 days in a sealed container.

You can rewarm the soup in a saucepan or microwave. Then, broil in the oven with shredded cheese.

Frequently Asked Questions

How Much Keto French Onion Soup Can I Eat?

This recipe serves 8 bowls. The serving size is 1 cup of soup and 1 slice of keto crouton and cheese.

The entire low-carb onion soup bowl, including bread slices, contains 7.8 grams of net carbs or 6.1 grams of net carbs without the keto bread.

Can I Replace The Wine?

Yes, you can use Worcestershire Sauce instead. But keep in mind that all the alcohol from the wine evaporates as the soup cooks.

Can I Skip The Xanthan Gum?

Yes, you don’t have to use xanthan gum it’s not absolutely necessary. The texture will be slightly more watery, but it’ll be delicious.

Enjoy the lovely Keto French recipe, and don’t forget to leave me a comment below if you made it and review it!

You can also follow me on Pinterest for more keto inspiration.