Keto French Onion Soup – Low Carb

This super tasty Keto French Onion Soup is coming at you with a rich, flavorful broth, sweet strands of caramelized onion, and a cheesy crouton topper. Seriously – what more could you ask for??? (Nevermind, don’t answer that…..)

I had to make a few concessions to get this to work. There are a little less onions in this Keto French Onion Soup than you might find in a more traditional version.

That’s OK though, because the delicious thyme flavored crouton soaks up the broth and makes this soup plenty hearty – and there are more than enough onions in there to get some in every spoonful.

These toppers though? I’m not sure what to call them – not quite a toast, not really a crouton, so…???? Your ideas welcome.

What I can tell you is that they make the perfect raft for the copious amounts of cheese you are going to add before digging in to this low carb French onion soup!

I would also add that these lil toppers are really, really versatile in their own right. I had a bunch in my freezer that I’ve since used to garnish other soups and stews to create a dumpling/biscuit/pie crust situation that was just perfection.

I’ve also used these toppers to put my bacon and egg on in the morning like a little open-faced breakfast sandwich. There’s a lot you can do with these – so much so that I almost gave them their own post on the blog, and I still might down the road.

All told, you can have a generous portion of this Keto French Onion Soup, complete with the topper and cheese and still come in at 10g net carbs.

It might sound like a lot when you’re shooting for only 20g net carbs per day, but it’s totally doable if you have almost no carbs with breakfast (bacon, eggs, avocado, and coffee are my go to) and a carb light lunch like tuna salad with romaine leaves.

Now you’ve got over 15g’s left for dinner which leaves plenty for this delicious and filling onion soup (and a glass of wine to go with it if you’re splurging.)

If you’re a French Onion Soup lover like me, then you’re going to find a way to make it work – and I promise you’ll be glad you did!

Here’s a few questions you might have that I’ll answer preemptively below:

Is French Onion Soup keto friendly?

As I mentioned, it can be a challenge to keep the carbs down in a French onion soup, but this version is absolutely keto friendly. Here is the breakdown of the nutrition info by component ( I will also supply this in the notes section of the recipe card.) If you want to keep the carbs down you can omit the topper, but it won’t be as filling and satisfying in my opinion.

Keto French Onion Soup: 113 calories, 7g fat, 8g carbs, 1g fiber, 7g net carbs, 3g protein
Thyme Topper: 245 calories, 19g fat, 5g carbs, 2g fiber, 3g net carbs, 16g protein
Cheese: 60 calories, 5g fat, 0g carbs, 0g fiber, 3g protein

Why do they call it French Onion Soup?

Fun fact – it’s called French onion soup because it has been common in France for centuries, where onions were cheap and plentiful during hard times. It eventually became a staple of Paris restaurants during the 18th century (where they just call it onion soup or “soupe à l’oignon”) and gained popularity as a first course served with toast and cheese, which is how it is still most commonly served today.

Now you know…

Is this onion soup vegetarian or vegan?

Typically, French onion soup gets its rich flavor from beef broth, which is what I used here. If you don’t eat beef you can substitute chicken broth for a lighter flavor. If you want to make this soup vegetarian or vegan, you can substitute a vegetable broth or stock, but the carbs may be a few grams higher than a broth made with meat. This recipe also includes Worcestershire sauce, which contains anchovies. You can replace it with an equal amount of coconut aminos for a similar flavor that is completely plant-based.

Can I use any kind of onion in French Onion Soup?

In a word, yes. I used yellow onions, which are traditionally used and give it a nice mellow flavor, but you can use white onions or even red onions if that’s what you have on hand – it will make very little difference in the end result.

Can I omit the wine in this Low Carb French Onion Soup?

Also yes. The white wine called for adds a subtle flavor that can be replicated by replacing it with an equal amount of water, and a teaspoon of balsamic or red wine vinegar.

What cheese can I top this low carb onion soup with?

Traditionally a French cheese like Comte, Gruyere, or even Swiss would be used to top a French Onion Soup – but if you can’t get it or aren’t a fan of the flavor, a mild cheese like mozzarella or muenster will work just as well. Cheddar will definitely stand out and compete with the flavor of the soup so I’d use it as a last resort unless you are looking for that kind of effect.

Ok, that should do it on the questions but if I’ve missed any let me know in the comments and I’ll answer them there and add them to this FAQ if necessary.

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