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This easy French Onion Soup gets it’s flavor from deeply caramelized onions and a punch of brightness from balsamic vinegar. With fresh herbs and plenty of melted cheese on top, you’ll want to make this recipe again and again.
Meggan’s notes
For the best French Onion Soup this side of the Atlantic, start by caramelizing your onions low and slow. As a classically-trained chef, I know the secret to deeply golden brown, mellow onions is to use a combination of olive oil and butter. Olive oil has a higher smoke point which helps prevent scorching, while butter adds richness in both taste and texture.
There is an optional ½ teaspoon sugar in the soup. A touch of sugar can help coax along the caramelization process, but feel free to leave it out. I use a combination of both chicken and beef broth here as well as fresh thyme and a dried bay leaf. These create a round, robust savory flavor that you’ll absolutely love.
Top of your soup bowl with crostini or croutons and plenty of cheese (slices or shredded), then broil until golden brown and bubbly. Gruyére is the most common cheese melted atop French Onion Soup, although any alpine-style cheese can work.
Table of Contents
Recipe ingredients
At a Glance: Here is a quick snapshot of what ingredients are in this recipe.
Please see the recipe card below for specific quantities.
Ingredient notes
- Olive oil: With a higher smoke point that butter, olive oil keeps the delicately-thin onion slices from scorching.
- Butter: Adds a richness to the flavor of the finished onions.
- Onions: Standard yellow onions work great, but so do white onions, sweet onions, or even red onions. Speed up prep time by running the onions through a food processor fit with the slicing disk rather than cutting onions by hand.
- Chicken broth: Make your own chicken broth from scratch or stock up on a couple boxes or four cans of your favorite supermarket brand.
- Beef broth: I like to make beef broth from beef base, a highly-concentrated beef stock similar to bullion cubes. My favorite is “Better than Bouillon” brand, a paste which is widely available and can turn up the savory flavor in any soup, stew, or sauce in seconds.
- Baguette: Toasting the baguette slices makes them even better at sopping up the maximum amount of broth while holding the melty cheese. If desired, substitute store-bought or homemade croutons.
- Gruyère: This pungent variety of Swiss cheese is used in many French recipes, also melts beautifully atop French Onion Soup. There is also Gruyere cheese made in France, and each country has their own protected designation seal.
Step-by-step instructions
- In a large Dutch oven over medium heat, melt olive oil and butter together. Add onions, sugar (if using), and ¼ teaspoon salt. Cook until the onions are starting to darken and caramelize, about 30 minutes.
- Stir in vinegar and scrape up the brown bits from the bottom of the pot. Add chicken broth, beef broth, thyme, and bay leaves. Simmer until reduced slightly, about 20 minutes. Season to taste with salt and pepper.
- Preheat oven broiler on HIGH. Place broiler-safe soup bowls on a rimmed baking sheet. Divide the soup evenly among the 8 bowls (about 1 cup each). Top each bowl with 1 or 2 baguette slices and cover with one slice of cheese (or ¼ cup shredded).
- Broil until the cheese is hot and bubbly, about 3 to 5 minutes. Remove from the oven and garnish with parsley, if desired.
Recipe tips and variations
- Yield: My homemade French Onion Soup recipe makes eight cozy (1-cup) servings that work well as a starter, side dish, or light main dish.
- Storage: Store leftovers covered in an airtight container in the refrigerator for up to 4 days.
- Make ahead: French Onion Soup can be made up to 3 days ahead and reheated (the flavor even improves as it sits). Save the baguette slices, cheese, and parsley for serving time.
- Freezer: French Onion Soup can be cooked, cooled, and frozen for up to 2 months (without the baguettes, cheese, and parsley). Thaw overnight in the refrigerator and reheat on the stove to serve.
- Make it a meal: True, soup is often a starter. But I prefer to make this the centerpiece of the meal, either lunch or dinner, and round out the spread with Beet Salad, No-Knead Bread, and a crisp French white wine.
Frequently Asked Questions
I use both! The butter offers the richest flavor and the olive oil helps prevent burning and gives the onions a smooth texture.
Gruyére cheese is a protected cheese made in Switzerland, while Gruyere cheese can also be made in France and has its own protected designation. The Swiss protected seal is red, while the French protected seal is blue. Both are white cheeses that melt well when sliced or shredded.
If you aren’t seeing any caramelization in the pan, you might not be cooking them enough. Resist the temptation to pull them off the stove once they start to brown—perfectly caramelized onions are supposed to have a dark color. Adding sugar will speed up the process.
You don’t have to stir them constantly, but scrape down the sides and bottom of the pan often to get an even cook.
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French Onion Soup
Equipment
- Lion's Head bowls (you definitely don't need these but they are fun)
Ingredients
- 2 tablespoons olive oil
- 1 tablespoon butter
- 3 pounds onions halved and thinly sliced (see note 1)
- 1/2 teaspoon sugar optional (see note 2)
- Salt and freshly ground black pepper
- 1/4 cup balsamic vinegar
- 6 cups chicken broth
- 2 cups beef broth
- 2 teaspoons fresh thyme minced, or ½ teaspoon dried thyme, plus more for garnish
- 1 bay leaf
- 1 baguette sliced and toasted (see note 3)
- 8 slices Gruyére cheese or Swiss cheese, or 2 cups shredded
Instructions
- In a large Dutch oven over medium heat, melt olive oil and butter together. Add onions, sugar (if using), and ¼ teaspoon salt. Cook until the onions are starting to darken and caramelize, about 30 minutes.
- Stir in vinegar and scrape up the brown bits from the bottom of the pot. Add chicken broth, beef broth, thyme, and bay leaf. Simmer until reduced slightly, about 20 minutes. Season to taste salt and pepper.
- Preheat oven broiler on HIGH. Place broiler-safe soup bowls on a rimmed baking sheet. Divide the soup evenly among the 8 bowls (about 1 cup each). Top each bowl with 1 or 2 baguette slices and cover with one slice of cheese (or ¼ cup shredded).
- Broil until the cheese is hot and bubbly, about 3 to 5 minutes, then remove from oven and garnish with fresh thyme if desired.
Notes
- Onions: Standard yellow onions work great, but so do white onions, sweet onions, or even red onions. Speed up prep time by running the onions through a food processor rather than cutting onions by hand.
- Sugar: A touch of sugar coaxes along the caramelization process, but it’s up to you if you want to add it.
- Baguette: Toasting the baguette slices makes them even better at sopping up the maximum amount of broth while holding the melty cheese. If desired, substitute store-bought or homemade croutons.
- Yield: My homemade French Onion Soup recipe makes eight cozy (1-cup) servings that work well as a starter, side dish, or light main dish.
- Storage: Store leftovers covered in the refrigerator for up to 4 days.
Nutrition
Meggan Hill is a classically-trained chef and professional writer. Her meticulously-tested recipes and detailed tutorials bring confidence and success to home cooks everywhere. Meggan has been featured on NPR, HuffPost, FoxNews, LA Times, and more.
Absolutely wonderful recipe; it tasted far better than any restaurant’s! Thank you for sharing!!
Judy P
You’re so welcome, Judy! I’m glad you loved it! – Meggan
When using better then bouillon advise folks how salty this product is maybe add first then adjust salt.
Hi Jimmy, thank you for writing and your suggestion. In step two, the directions allow seasoning to taste to account for the different amounts of salt that could be in broths. Thanks again and I hope you love this soup! – Meggan
This was really easy and full of flavor. My husband especially loved it!
This is very easy and tastes just like a restaurant.
How much olive oil do I use if I use the instant pot?
Great presentation