Onion Burger with Gruyère Fondue Sauce

Onion Burger with Gruyère Fondue Sauce is a kicked up gourmet burger for your Holiday cookout. Hamburgers fresh off the grill with that charcoal taste, potato salad, deviled eggs, baked beans, and watermelon. Those memories are etched in our minds and just mentioning the Holiday has an impact on our senses – especially taste and smell. Times may change, but the palate wants what the palate wants! For your next holiday cookout we suggest our Onion Burger with a Gruyère Fondue Sauce!

A burger made with onions is a classic and cheese is the usual topping. However, everyone today seems to have felt the Rachel Ray “effect.” The self-proclaimed “Queen of the Burger” has certainly made more variations than one can count. So why should we be any different? Let’s take the classic burger and cheese and add some flair – low carb, of course.


We keep our burger simple. An 80-20 blend is our choice – the fat adds so much flavor and moisture. No one likes a dry burger. To the basic ground beef mix we add chopped onion, some garlic, and Worcestershire. In the past, we often made a burger using our basic meatloaf recipe. Lately, we just want that great grilled flavor of a simple burger and add the toppings to create a unique recipe.

The Gruyère cheese came to mind this year. Many will use a classic American cheese, or swiss, or even provolone to top a burger. Gruyère melts well and has a unique taste. You will find it in a quiche or fondue and in melted cheese sandwiches and cordon bleu recipes. It is more frequently used in French onion soup. Our fondue sauce works well with a burger. It is creamy, nutty, and with a bit of wine will add a new memory for the 4th.

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The finishing touch on our holiday burger will continue the French theme with deeply caramelized onions. We make our onions with thyme and Worcestershire and a good bit of butter. A great topping for any burger, and especially good for our Onion Burger with Gruyère Fondue Sauce. The onions need to cook low and slow.

What would a burger be without a tasty bun? For many months we have been eating bun-less burgers or in a lettuce holder. For this holiday we went all out and used a large muffin pan and our low-carb bread recipe to make a Tasty Low Carb hamburg bun. Since posting this recipe, Joanie has also been using our own home-made yeast burger buns for these burgers.

Preparation Tips

Start with the caramelized onions first since they will take some time to turn a deep caramel color and soften. The secret is to cut your onions thin (a sweet onion is best) and brown them slowly in butter on low heat. We like a little thyme and the Worcestershire near the end of the process adds both color and flavor. Be patient – you will be rewarded with a great topping.

The key to the Guyère fondue sauce is the white wine. A dry wine works best. Try a Riesling or Chardonnay for a stronger flavor with the mellow cheese. The fondue sauce should pour easily over the burger without being too runny. If you remember the fondue years you will enjoy the taste of the beef topped with a fondue sauce.

Assemble your Onion Burger with Gruyère Fondue Sauce in the usual way. A little dab of the sauce on the bottom of the bun, lettuce, then the burger. More fondue sauce on top of the burger and then capped with the caramelized onions liberally placed before topping with your low-carb bun.

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Frontier Ground Organic Fair Trade, Nutmeg, 1.9 Ounce
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  • Allergen Information: Abalone Free

Onion Burger with Gruyère Fondue Sauce – Call it an Onion Soup Burger!

Try some garlic parmesan zucchini fries on the side or our smoky bacon deviled eggs to complete the meal. Have a cold low-carb beer, enjoy the Holiday, and our simple, but tasty Onion Burger with Gruyère Fondue Sauce. Tastes like onion soup!

Onion Burger with Gruyère Fondue Sauce

Recipe by Joanie and Chris
4.9 from 27 votes
Course: Snack MealsCuisine: AmericanDifficulty: Easy


Prep time


Cooking time




Net Carbs


Total time



Low Carb Onion Burger with Gruyère Fondue Sauce tastes just like a French onion soup burger – only with a creamy Tasty Low-Carb fondue sauce.

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  • Caramelized Onions
  • 1 tablespoon 1 tablespoon butter

  • 1 large 1 large onion sliced thin

  • 1/2 teaspoon 1/2 teaspoon thyme ground

  • 1/2 teaspoon 1/2 teaspoon Worcestershire

  • 1/8 teaspoon 1/8 teaspoon sea salt

  • 1/8 teaspoon 1/8 teaspoon pepper

  • Gruyere Fondue Sauce
  • 4 ounces 113 ml white wine dry

  • 8 ounces 227 g Gruyere cheese shredded

  • 1/8 teaspoon 1/8 teaspoon ground nutmeg

  • 1/8 teaspoon 1/8 teaspoon sea salt

  • Burger
  • 16 ounces 454 g ground beef 80-20 blend

  • 1/4 medium 1/4 medium onion chopped

  • 2 cloves 2 cloves garlic chopped

  • 1 teaspoon 1 teaspoon Worcestershire

  • 1/2 teaspoon 1/2 teaspoon sea salt

  • 1/8 teaspoon 1/8 teaspoon pepper


  • Caramelized Onions
  • Melt the butter in a medium skillet, pre-heated medium.
  • Add the thinly sliced onions to the melted butter and cook for 5 minutes until they wilt. Add the thyme, salt, and pepper and cook for another 10 minutes until they start to brown.
  • Add the Worcestershire sauce and cook for another 10 minutes – set aside.
  • Gruyere Fondue Sauce
  • Simmer the wine in a saucepan over medium heat for 5 minutes. Add the Gruyere cheese a little at a time until all melted – storing as you go to form a creamy sauce.
  • Add the nutmeg and sea salt. Keep warm until ready to assemble – consistency should be easy to pour over the burger, but not too runny. Adjust with more cheese or wine until just right.
  • Burger
  • Mix all of the burger ingredients in a large bowl with your hands until well incorporated. Form into patties and press your thumb in the middle of each to indent for even cooking.
  • Pre-heat grill pan to medium and spray lightly with olive oil spray. Fry until the burgers are done – about ten minutes. Flip only once and do not press down.
  • Assemble as follows – On bottom of low-carb burger bun, spread a dab of Gruyère fondue sauce. Follow with a piece of lettuce. Then the burger  and pour Gruyère cheese fondue sauce over the burger. Finally, place a good helping of caramelized onions on top and then add the burger bun lid.


Chef’s Notes

  • If you are counting, add the nutrition information for a low-carb bun

Nutrition Facts

  • Calories: 1034.5kcal
  • Carbohydrates: 7g
  • Protein: 74g
  • Fat: 87.8g
  • Saturated Fat: 42.5g
  • Cholesterol: 300.8mg
  • Sodium: 1944.1mg
  • Potassium: 923.9mg
  • Fiber: 1.6g
  • Sugar: 5.2g
  • Vitamin A: 1400IU
  • Vitamin C: 5.8mg
  • Calcium: 1224.1mg
  • Iron: 29.2mg

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  1. I couldn’t get the cheese sauce to thicken! Any suggestions?

    • Joanie and Chris

      If the ingredients are correct, this would usually mean the wine did not reduce enough. To correct, I would add more cheese and continue to stir until you get the right consistency. We love the sauce and even use it as a dip for veggies after it cools slightly. You can see by the pictures of our Onion Burger that the cheese has setup as it cooled. Try again and thank you for the question . . . Joanie.

      • That was it! I reduced the wine more and the sauce had the proper consistency this time. So good (we added some sauteed mushrooms to the burger as well), thanks for the recipe

        • Joanie and Chris

          So pleased it worked out for you. Glad you enjoyed the sauce, it makes the burger. I hope you will try more of my creations . . . Joanie.

  2. The cheese doesn’t melt good!!!!
    It just turns into a soft lump.

    • Joanie and Chris

      Try a constant stir while melting. Make sure you heat the white wine. Sometimes Swiss or Emmentaler cheeses will lump, but usually the solution is to add a little Gruyere. I hope you will try again, I have never had a problem. Thanks for the comment . . . Joanie.

  3. Hi!

    Will this recipe work if I wanted to double the fondue sauce?

    • Joan and Chris

      You can certainly double the fondue sauce recipe if you would like more on each burger. We find it is enough for two servings. There is actually a “servings” drop-down window on each recipe card where you can manually change the number off servings and it will change the recipe amounts accordingly. So, just change the servings to 4 and you will have doubled the recipe amount for the fondue automatically. We love it as a burger topping and hope you do, as well. Thanks for the comment . . . Joanie.

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