Name: Keto French Onion Soup
Prep time: 10 min
Cook time: PT-487037H54M29S
Total time: 50 min
Cuisine: French
Ingredients: 2 tablespoons butter; 4 large yellow onions, thinly sliced; 3 cloves garlic, minced; 4 cups beef broth (preferably low-sodium); 1 cup dry white wine (optional; can use extra broth if preferred); 1 teaspoon thyme (dried or fresh); 1 teaspoon rosemary (dried or fresh); Salt and pepper, to taste; 1 tablespoon balsamic vinegar; 1 1/2 cups shredded Gruyère cheese (or Swiss cheese); Fresh parsley, chopped (for garnish)

Why You’ll Love This Recipe

Keto French Onion Soup gives you the comforting flavors of the original version, but without the carbs from the bread. The caramelized onions create a rich, sweet base, while the beef broth adds depth and savory goodness. Topped with gooey melted cheese, this soup is sure to warm you up and leave you feeling satisfied. It’s perfect for anyone following a keto or low-carb diet but doesn’t want to miss out on the classic flavors. Plus, it’s incredibly easy to make and great for meal prep!

Ingredients

2 tablespoons butter
4 large yellow onions, thinly sliced
3 cloves garlic, minced
4 cups beef broth (preferably low-sodium)
1 cup dry white wine (optional; can use extra broth if preferred)
1 teaspoon thyme (dried or fresh)
1 teaspoon rosemary (dried or fresh)
Salt and pepper, to taste
1 tablespoon balsamic vinegar
1 1/2 cups shredded Gruyère cheese (or Swiss cheese)
Fresh parsley, chopped (for garnish)

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

Directions

In a large pot, melt the butter over medium heat. Add the sliced onions and cook, stirring occasionally, until the onions are softened and caramelized, about 25-30 minutes. Stir occasionally to prevent burning, and if needed, add a splash of water to prevent the onions from sticking.
Add the minced garlic to the onions and cook for another 1-2 minutes, until fragrant.
Pour in the beef broth, wine (if using), thyme, rosemary, salt, and pepper. Bring the soup to a simmer and cook for an additional 15-20 minutes, allowing the flavors to meld together. Adjust seasoning as needed.
Stir in the balsamic vinegar for added depth of flavor and balance.
Preheat the broiler on your oven.
Ladle the soup into oven-safe bowls. Top each bowl with a generous amount of shredded Gruyère cheese.
Place the bowls under the broiler for 2-4 minutes, or until the cheese is melted and golden brown. Watch closely to avoid burning.
Garnish with fresh parsley and serve hot.

Servings and Timing

Servings: 4
Prep time: 10 minutes
Cook time: 40-45 minutes
Total time: 50 minutes

Variations

No wine: If you prefer not to use wine, you can substitute with more beef broth or a splash of apple cider vinegar for acidity.
Add mushrooms: For extra texture and flavor, you can sauté sliced mushrooms with the onions as they caramelize.
Vegan version: Swap the butter for olive oil and use vegetable broth in place of the beef broth. For a dairy-free version, omit the cheese and try adding coconut cream for a rich, creamy texture.
Cheese variety: Try using different cheeses like mozzarella or cheddar if you prefer a different flavor profile for the melted topping.

Storage/Reheating

Storage: Leftover Keto French Onion Soup can be stored in an airtight container in the refrigerator for up to 3 days.
Freezing: You can freeze the soup for up to 2-3 months. Let the soup cool completely before transferring it to a freezer-safe container. To reheat, thaw in the fridge overnight and reheat on the stovetop.
Reheating: Reheat on the stovetop over medium heat, adding extra broth if needed. If you’ve already melted the cheese, it’s best to top the soup with fresh cheese before broiling it again if desired.

FAQs

Can I skip the wine in this recipe?

Yes, you can substitute the wine with additional beef broth or use a splash of apple cider vinegar for some acidity without the alcohol.

Is this soup keto-friendly?

Yes, this recipe is keto-friendly! It is low in carbs because it doesn’t use bread or any high-carb ingredients, just rich broth and caramelized onions.

Can I use a different cheese?

Yes, you can use different cheeses like Swiss, mozzarella, or cheddar. However, Gruyère is the traditional cheese used in French onion soup and provides the best melt and flavor.

Can I make this soup ahead of time?

Yes, this soup can be made ahead of time. Store it in the refrigerator for up to 3 days and reheat on the stove. If you make it ahead, wait to broil the cheese until right before serving.

How do I caramelize the onions properly?

The key to properly caramelizing onions is to cook them slowly over low to medium heat, stirring often to prevent burning. Be patient; it can take 25-30 minutes to get the right golden-brown color.

Can I freeze Keto French Onion Soup?

Yes, you can freeze the soup without the cheese topping. When ready to serve, reheat and add fresh cheese before broiling.

Can I use a different type of broth?

Yes, you can use vegetable broth for a vegetarian version or chicken broth if preferred. Beef broth gives the soup a rich, deep flavor, but other broths can work in a pinch.

Is this soup very sweet from the onions?

The onions do caramelize and become sweet, but the balance from the beef broth, wine (if used), and balsamic vinegar keeps the soup from being overly sweet. It adds depth and richness instead.

How can I make this soup more filling?

If you want to make this soup heartier, you can serve it with a side of keto bread or add some low-carb vegetables like cauliflower or zucchini.

What can I serve with this soup?

This soup pairs wonderfully with a light side salad, keto bread, or even some roasted vegetables for a more complete meal.

Conclusion

Keto French Onion Soup is a flavorful, satisfying low-carb version of the classic that’s just as comforting as the original. With its rich, caramelized onions, savory beef broth, and gooey melted cheese, this soup will quickly become a favorite for anyone on a keto or low-carb diet. It’s easy to make, perfectly portioned, and can be customized to suit your taste. Whether you’re craving a bowl of comfort on a chilly night or simply looking for a delicious, hearty meal, this keto-friendly French onion soup is the answer