French Onion Soup has always been a favorite of mine, and this Keto French Onion Soup delivers on the classic flavors. With a rich, perfectly seasoned broth, garlic, and onions, all topped off with Gruyere cheese, you have a hearty soup that is impossible not to love. Try it once, and you will be hooked.
Onion Soup is best when the onions are caramelized to perfection. This French Onion Soup recipe achieves that. It's also low in carbs, gluten-free and keto-friendly
Give it a try, and I think you will agree, this easy recipe deserves to become a cold-weather habit.
Ingredients for Making French Onion Soup Keto
- Butter: I like the richness that butter adds to the dish, but you could use all oil if you prefer.
- Oil: I used avocado oil, but you can use your favorite keto-friendly oil. Just be conscious of the smoke point.
- Onion: I use yellow onion.
- Thyme: Either fresh or dried will work.
- Garlic: I prefer fresh garlic here, but you could use dried as well.
- Sherry: I like the flavor of sherry, but you could use dry white wine, red wine, or simply add more broth to the soup.
- Broth: Homemade beef stock will enhance the flavor, but you can't buy broth if you don't have time to make it. I like to use beef bone broth because it is thicker and rich in flavor.
- Coconut Aminos: This is a gluten-free and soy-free alternative to soy sauce.
- Salt and Pepper: Taste at the end of cooking and adjust the amount of salt to your liking.
- Xanthan Gum: This is optional but helps to thicken the soup.
- Cheese: I used Gruyere cheese, but Swiss cheese will work as well. It is not traditional, but cheddar or mozzarella could be used as well.
- Bread: If you would like to melt the cheese on a keto-friendly bread, you can. Or make my Keto Breadsticks and leave off the cheese until just before serving the soup.
Frequently Asked Questions
Unfortunately, most French Onion Soups are not keto-friendly. This is because they use a large number of onions - sometimes as many as six - and then are topped with cheesy bread.
We keep this recipe keto-friendly by reducing the number of onions and either omitting the bread altogether or choosing a keto-friendly bread.
There are several reasons that your onions may not have properly caramelized.
The first is that they were sliced too thin. You want them to be at least ⅛" thick. Shaved onions can burn quickly.
Secondly, if you skip the avocado oil, which raises the smoking point of butter, this can cause the onions to burn.
Lastly, having the heat too high to try to speed up the process can cause them not to caramelize.
I recommend using yellow onions for French Onion Soup, but you could also use a mix of onions if you like.
I used beef broth as the base of this soup, so it is not. If you would like to make vegetarian keto french onion soup, simply swap the beef broth for vegetable broth.
Yes. Sherry or wine adds an additional layer of flavor in this keto french onion soup recipe, but you can omit it if you don't have either on hand. Just add more broth.
Tools Needed to Make French Onion Keto Soup
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- Broiler Safe Soup Crocks or Soup Bowls
- Large Saucepan
- Soup Ladle
Can You Make French Onion Keto Soup Ahead?
Yes! This can be made ahead of time.
Store leftovers in a sealed container in the refrigerator for up to four days.
Can French Onion Soup Be Frozen?
You can freeze leftovers for up to three months.
How to Make Keto French Onion Soup
First, start by heating the butter in oil in a large saucepan.
Add the onion slices and fresh thyme and cook for 10 minutes. Reduce the heat, and cook for another 30 minutes.
Stir in the garlic and cook for another minute.
Add the sherry and cook for 2 minutes, scraping up any browned bits.
Add the broth, coconut aminos, seasonings, and xanthan gum.
Simmer over medium heat for 15 minutes.
Transfer the soup to broiler safe soup crocks. Sprinkle with cheese.
Broil until the cheese is melted.
Garnish with sprigs of thyme if desired.
More Keto Soup Recipes to Try!
- Give it a try and you will see why this Keto Mushroom Soup is a fan favorite. It is super-easy to make and oh-so-delicious.
- No need to miss potatoes when you have this Keto Cauliflower Soup. All the flavors of loaded potato soup in a low carb version you will love.
- Keto Chicken Pot Pie Soup has the flavors of your favorite casserole and a delicious soup that is so filling.
- This Keto Broccoli Cheese Soup is pure cheesy comfort food. Give it a try and you will be hooked.
Keto French Onion Soup
- ¼ cup butter
- 2 tablespoons avocado oil
- 2 small yellow onions halved and sliced thin(reduce to 1 for strict keto)
- 1 tablespoon fresh thyme or one teaspoon dried
- 1 teaspoon minced garlic
- ¼ cup cooking sherry
- 4 cups beef broth
- 2 tablespoons coconut aminos
- Salt and pepper
- ½ teaspoon xanthan gum
- 1 ½ ounces shredded Gruyere cheese
- Optional: keto bread cut into rounds
- Heat the butter and avocado oil in a large saucepan over medium-high heat.
- Add the onions and thyme and cook, stirring occasionally, for 10 minutes.
- Reduce heat to medium and cook for another 30 minutes, until the onions are a deep golden brown.
- Stir in the garlic and cook for 1 more minute.
- Add the cooking sherry and cook for 2 minutes, scraping up any browned bits.
- Add the broth, coconut aminos, salt, pepper, and xanthan gum. Simmer over medium heat for at least 15 minutes.
- Preheat a broiler to high and ladle soup into broiler-safe soup crocks. Sprinkle with cheese. Alternatively, you can toast bread, add it to the crocks and top with the cheese.
- Broil for 2 minutes, until the cheese is bubbly.