Easy Gluten-Free French Onion Soup

This is an easy, restaurant-quality gluten-free French onion soup made with simple ingredients, including caramelized sweet onions, broth, white wine, butter, seasonings, and a melty layer of Gruyère cheese. If you want a classic French onion soup that is both gluten-free and easy to make for weeknight cooking, this recipe checks every box.

Ingredient Notes:

For the full list of ingredients and amounts, please go to the recipe card below.

• Sweet Onions – Vidalia onions give the best flavor for this soup because they are naturally sweet, mild, and perfect for caramelizing. Hawaiian sweet onions also work well. Yellow onions caramelize nicely but can taste a little sharp at first. Slice the onions into uniform slivers so they cook evenly.
• Beef Broth – Low-sodium broth is my preference, so you can control the salt level. Make sure the broth you use is labeled gluten-free.
• Butter – Use salted or unsalted butter.
• White Wine – White wine adds depth and brightness to the broth. Use an inexpensive bottle; there is no need to use anything fancy. Note: I have not tested red wine in this recipe.
• Thyme – I used dried thyme.
• Coconut Sugar – You can also use brown sugar. This small amount is not for sweetness. It helps the onions caramelize faster and more evenly.
• Garlic – I prefer freshly minced, but jarred is fine.
• Bay Leaf – For flavor, remove after cooking.
• Gruyere Cheese – This is the best part…it melts beautifully, and its flavor works with the caramelized onions.
• Milton’s Crackers – If you can’t find Milton’s, make some Gluten-Free Croutons.

How to Make Gluten-Free French Onion Soup (Step-By-Step)

Remove the onion peel and cut off both ends. Cut the onion in half. Place the flat side down on the cutting board and thinly slice the onions into half-moon shapes.

Melt the butter in a pot and heat on medium-low heat.

Testing note: The wider the pot, the better the onions caramelize. They need surface area.

How to Caramelize Onions for French Onion Soup

Caramelizing onions is the step that makes this soup taste as if it came from a bistro kitchen. Here is what to know before you start:

• Slice thinly and uniformly. Thick pieces will not soften at the same rate.
• Use a wide pot. More surface area = more even browning.
• Low heat is key. High heat scorches before caramelization happens.
• Stir occasionally, not constantly. Too much stirring prevents browning.
• The onions will reduce dramatically. Four large onions may become one small pile. This is normal.
• Color is your cue. Aim for deep gold, not dark brown.

If your onions ever taste bitter, it is likely that they cooked too fast or burned slightly on the edges.

Add the thinly sliced onions and sauté for 5 minutes, until they soften.

Add coconut sugar (or brown sugar) and spices. I usually wouldn’t add sugar to a soup recipe, but the sugar helps the onions caramelize. Adding the sugar here helps the onions caramelize.

Cover and cook the onions over low heat for 20-30 minutes, or until caramelized, as shown in the next picture. If the onions start sticking or browning too quickly, your heat is too high.

Add the caramelized onions to a soup pot.

Deglaze the onion pan. Pour in the white wine and scrape up any brown bits from the bottom of the pan. Pour this into the soup pot with the caramelized onions.

To deglaze, pour in the white wine and scrape up any brown bits from the bottom of the pan.

Pour in the beef broth. Add two bay leaves and thyme. Cover and simmer over low heat for 1 hour.

Use a ladle to fill bowls with the gluten free French onion soup.

This is my favorite part. Grab a bag of Milton’s Gluten Free Sea Salt Crackers. Take about 4 or 5 crackers and place them on top of the onion soup.

Top with a thick slice of gruyere cheese. Place the soup bowls in a baking dish and place under a broiler until the cheese melts. Serve the soup hot with Milton’s Gluten Free Crackers.

Frequently Asked Questions:

More Gluten-Free Soup Recipes to Try:

Need another great soup recipe? Here are the recipes my family loves:

• This Instant Pot Vegetable Soup with Chicken makes a great lunch to take in a thermos.
• If you love soup, this Unstuffed Pepper Soup is delicious.
• My Grandma’s Chicken Soup From Scratch is perfect for cold and flu season.
• Everyone will love this creamy Gluten-Free Fish Chowder recipe.

This post was updated from an old May 2018 post with more detailed instructions.