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Keto French Onion Soup (Low-Carb, Ready in 45 Minutes)

Keto French Onion Soup (Low-Carb, Ready in 45 Minutes)

Rich, cheesy Keto French Onion Soup made with caramelized onions, beef broth, and a bubbling low-carb cheese topping. Only 7g net carbs per bowl.
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Prep Time 15 minutes
Cook Time 30 minutes
Total Time 26 minutes
Servings: 4
Course: Appetizer
Cuisine: French
Calories: 310
Ingredients Equipment Method Video Notes

Ingredients
  

  • 3 tablespoons butter or ghee
  • 2 tablespoons olive oil
  • 4 large yellow onions thinly sliced (about 2.5 lbs)
  • 1 teaspoon salt plus more to taste
  • 1 teaspoon sugar-free brown sugar substitute optional, helps caramelization
  • 2 cloves garlic minced
  • 1/4 cup dry white wine or dry sherry optional, can substitute broth
  • 6 cups beef bone broth
  • 2 teaspoons fresh thyme leaves or 1/2 teaspoon dried
  • 1 bay leaf
  • 1 tablespoon Worcestershire sauce check label for sugar content
  • 1/4 teaspoon xanthan gum optional, for body
  • Black pepper to taste
  • 8 oz Gruyère cheese shredded
  • 1/2 cup grated Parmesan cheese

Equipment

  • Large heavy-bottomed Dutch oven or soup pot
  • Chef’s knife and cutting board
  • Wooden spoon or heatproof spatula
  • Measuring spoons and measuring cup
  • Ladle
  • Oven-safe soup crocks or bowlsBaking sheet, if broiling several bowlsOven with broiler functionOven mitts

Method
 

Caramelize the onions.
  1. Melt the butter with the olive oil in a large Dutch oven over medium heat. Add the sliced onions and 1 teaspoon salt. Cook, stirring occasionally, for 35–45 minutes, until deeply golden brown and jammy. Stir in the sugar substitute halfway through to help browning. Lower the heat if they start to catch.
Build the base.
  1. Add the garlic and cook for 1 minute until fragrant. Pour in the wine (if using) and scrape up any browned bits from the bottom of the pot.
Simmer the broth.
  1. Add the beef bone broth, thyme, bay leaf, and Worcestershire sauce. Bring to a simmer and cook uncovered for 15–20 minutes to let the flavors meld. If using xanthan gum, whisk it in during the last few minutes to lightly thicken the broth. Remove the bay leaf and season with pepper and extra salt to taste.
Broil with cheese.
  1. Preheat the broiler. Ladle the soup into oven-safe bowls, top generously with Gruyère and a dusting of Parmesan, and broil for 2–4 minutes until bubbling and browned in spots. Watch closely so the cheese doesn't burn.
Serve hot,
  1. ideally with a low-carb bread slice on the side if you want something to dip.

Video

Notes

Use a heavy-bottomed Dutch oven for even caramelization, and broil the soup only in heatproof bowls.
Don’t rush the onions—slow caramelization creates the soup’s deepest flavor. Keep the heat low and stir occasionally until they are soft, glossy, and deep golden brown.