Bistro French Onion Soup

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This Bistro French Onion Soup Recipe is completely homemade and perfect for a chilly day! Caramelized onions, melty cheese, and crusty bread make this one of the best soups ever. It's easy enough for a novice and delicious for everyone in the family.

Now that the weather has cooled off, it's definitely soup season! One of my favorite soups is this Bistro French Onion Soup, probably because there is a lot of melty cheese involved.

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Why You'll Love This Recipe
Key Ingredients Needed for Bistro French Onion Soup
How to make This Super Easy French Onion Soup
Expert Tips for This Recipe
Recipe FAQs
Bistro French Onion Soup Recipe

Why You'll Love This Recipe

You will fall in love with this bistro-style French Onion Soup recipe for its rich and savory broth, caramelized onions, and the irresistible combination of melted cheese and toasted bread topping that creates a heavenly experience. Not only will you have a warm and delicious soup to serve, like my Roasted Heirloom Tomato Soup, but your house will also smell amazing when the onions are caramelizing!

Key Ingredients Needed for Bistro French Onion Soup

Yellow Onions: Yellow onions are commonly used in French onion soup for their sweet and rich flavor when caramelized. They add depth and complexity to the soup.
Beef Broth: Beef broth is the base of the soup and provides a rich and savory flavor. Chicken or vegetable broth can be substituted if preferred.
Baguette: A baguette is typically sliced and toasted to create the iconic bread topping for French onion soup. It adds a crispy texture and absorbs the flavors of the soup.
Gruyere Cheese: Gruyere cheese is traditionally used for French onion soup. It has a nutty and slightly sweet flavor that melts beautifully and forms a golden crust on top of the soup.

*See the recipe card for the complete list of ingredients and quantities.

How to make This Super Easy French Onion Soup

Step 1: Add the butter and oil and melt over medium-low heat. After the butter stops bubbling, add the onions and stir to coat the onions. Cover and cook for 15 minutes on low.

Step 2: Remove the lid and add salt, pepper, and sugar to get the caramelization going. Continue to cook on medium-low heat for 25-30 minutes, stirring often, until the onions are nice and brown.

Step 3: Add the flour to the onions and stir for about 60 seconds. Add the broth, wine, and herbs to the onions, and cook partially covered on low heat for about 40-45 minutes.

Step 4: While the soup is cooking, slice the bread into slices or large cubes and brown under a broiler for a few minutes to get them crispy.

french onion soup with bread and cheese before broiling.

Step 5: Pour the soup into individual oven-safe serving bowls. Top with the bread slices or cubes and then a generous amount of cheese.

french onion soup with thyme and melted cheese.

Step 6: Place the bowls under the broiler in the oven until the cheese is melted and bubbly. Remove from oven and allow to cool for a few minutes before serving.

Expert Tips for This Recipe

Slow and Low Caramelization: Take your time when caramelizing the onions. Cook them slowly over low heat to allow the natural sugars to develop and create deep, rich flavors. This process can take anywhere from 30 to 45 minutes, but it's worth the patience for the best results.
I use a Dutch oven to cook the onions and soup. The heat of the cast iron helps with the onion caramelization.
Use a Combination of Butter and Olive Oil: Using a combination of unsalted butter and olive oil helps prevent the butter from burning while adding a delicate fruity flavor to the onions.
Season Gradually: Add salt and freshly ground black pepper in stages throughout the cooking process. This allows you to layer the flavors and adjust the seasoning to your preference.
Let it Rest: After the soup is cooked, allow it to rest for a few minutes before serving. This allows the flavors to meld together and results in a more harmonious taste.

Recipe FAQs

How Many Carbs in French Onion Soup?

My version of French onion soup has 51.3g of carbs per serving. Most of this is from the crusty baguette on top. So if you are watching your carbs, omit the bread.

How do I Make This Recipe Gluten-Free?

This recipe is pretty simple and there are so many ways to adjust it to your liking. If you are gluten-free, leave out the flour.

What type of onions to use for Bistro French Onion Soup?

I usually use basic yellow or white onions for French Onion Soup, but you can use any onion you like. Yellow and white onions create a nice sweetness and are usually the least expensive.

You can usually find either of these in bulk bags which makes it even more convenient and cost-efficient. Red onions will work as well but tend to be a little more bitter and sweet onions are delicious but tend to be a little more expensive.

Can I Use a Different Type of Cheese?

Gruyere cheese is the most common cheese used for French onion soup. I highly recommend it not only for its melty quality but for the nutty and salty flavors you get from Gruyere.

However, if you do not have or like Gruyere, you can also use mozzarella or Monterey cheese since they both melt well. Most grocery stores have cheese experts in the cheese section and they could guide you as well.

If you get a chance to make this Easy French Onion Soup Recipe, tag me on Instagram or Facebook and show me, or leave a review below! You can also follow me on Pinterest and sign up for my e-mail list to receive more fun and delicious recipes in your inbox.