French Onion Soup Recipe
This authentic French Onion Soup tastes like it came straight from Paris, but non, it’s made right in your kitchen.
Prep Time 10 minutes
Cook Time 50 minutes
Total Time 1 hour
Servings 8 (1 cup each)
- 2 tablespoons butter
- 3 pounds onions halved and thinly sliced (see notes)
- Salt and freshly ground black pepper
- 1/4 cup balsamic vinegar
- 6 cups chicken broth
- 2 cups beef broth (see notes)
- 2 teaspoons minced fresh thyme or 1/2 teaspoon dried thyme
- 2 bay leaves
- 1 baguette sliced and toasted (see notes)
- 8 slices Swiss cheese or 2 cups shredded Swiss cheese
- 1/4 cup chopped fresh parsley for garnish, optional
In a large Dutch oven over medium heat, melt butter. Add onions and 1/2 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 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 1/4 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.
How to make French Onion Soup in a Slow Cooker:
- You can use any onions in this recipe. I used standard onions, but you could use sweet or red or white. No matter which onion you use, the low, slow caramelization process will mellow out any harsh flavors.
- I use Better than Bouillon beef base for beef broth (2 teaspoons + 2 cups water). If using canned beef broth, substitute 1 (14.5 ounce) can beef broth. You can add another 1 1/2 ounces water to make up for the difference if you want, but overall you'll still have about the same amount of soup. So don't sweat it. French Onion Soup isn't science thank goodness!
How to make French Onion Soup in the Instant Pot:
- In the crock pot, combine sliced onions, butter and salt.
- Stir the onions well and cook on LOW 8 to 10 hours. Let the onions cool and store in the refrigerator until you're ready to make the soup.
- On the day you plan to serve the soup, you can add the remaining soup ingredients to the slow cooker and cook on LOW for 6 to 8 hours.
- Then top the individual soup bowls with bread and cheese, or homemade croutons.
How to Toast Baguette Slices:
- Add sliced onions, thyme, bay leaf, butter, and olive oil to the Instant Pot.
- Cover and seal the lid and set for 20 minutes on the manual function. When finished, quick release the steam.
- Remove the cover and turn on the sauté function. Cook on the sauté function for about another 20 minutes to allow the extra liquid to evaporate and to get that lovely golden brown color. You only need to stir the onions occasionally.
- Once you've made the caramelized onions in the Instant Pot, keep the sauté function on and deglaze the pot with the balsamic vinegar.
- Then add the remaining soup ingredients to the pot, and bring to a simmer and let cook until the soup thickens, about 10 minutes.
- Then taste and adjust the seasonings as needed before serving.
You could also substitute croutons.
- Preheat oven to 350 degrees.
- Cut 1 baguette into slices and brush with olive oil (about 1/4 cup oil for 1 baguette).
- Arrange baguette slices in a single layer on a rimmed baking sheet.
- Bake until lightly toasted, about 15 minutes.