French Onion Soup

Article by Layla Khoury-Hanold

With its caramelized onion base, rich broth and cheesy croutons, French onion soup is one of the ultimate comfort food dishes. Although this soup is a French bistro classic, it is easy to make at home and an inexpensive way to feed a crowd. In his recipe, chef Tyler Florence shares his simple tips for making restaurant-worthy French onion soup, including how to caramelize onions, the key ingredients for building savory flavor and how to make croutons with a golden, bubbly, cheese-pull worthy finish.

How to Make French Onion Soup Like a Pro

Caramelize the onions in butter and don’t rush the process. Tyler adds a whole stick of butter to a big pot, which he acknowledges sounds like a lot, but this recipe serves 6 people plus leftovers. Once the butter has melted, he cooks sliced onions and smashed garlic cloves over medium heat until very soft and caramelized, and blonde in color, about 25 minutes. Don’t rush the process, allowing the onions to cook the full amount of time is the key to building the base of French onion soup.

Add wine and herbs to build another layer of flavor. Tyler adds a half bottle of last night’s red wine to deglaze the pan, scraping up the flavor bits on the bottom. He also adds whole sprigs of fresh thyme and bay leaves. You’ll want to simmer the mixture until the wine has evaporated and the onions are dry and have taken on a golden, purple-y raisin color, about 5 minutes.

Make a roux to thicken the soup. Tyler dusts the onions with a couple heaping tablespoons of flour and stirs it in. Be sure to lower the temperature to medium-low to allow the mixture to simmer, prevent the flour from burning and cook out the raw flour taste.

Add beef broth for a traditional French onion soup base. Tyler adds beef broth to create a traditional French onion soup flavor profile. Be sure to buy low-sodium beef broth help control how much salt goes into the pot.

Make the cheese-toast croutons. Tyler ladles soup into classic French onion soup crocks (you can also use coffee cups or oven-safe bowls), floats a couple baguette slices on top and tops them with buttery Gruyère cheese. He places the soup crocks on a baking sheet and broils them in the oven until the bread is toasted and the cheese is melted, bubbly and golden-brown.

French Onion Soup Onions

The best onions for French onion soup are yellow or Spanish onions, which have a balanced sweet-savory flavor profile that work well for caramelizing. You can use white onions, but they don’t have the same savory depth as yellow caramelized onions. Avoid sweet onions as they will become even sweeter once caramelized, as well as red onions, which are best suited to quick-cooking techniques.

For French onion soup, you’ll want to slice the onions into thin half-moons. For tips on the best technique for slicing onions, check out our guide How to Cut an Onion.

How to Caramelize Onions

For French onion soup, you’ll want to use blonde caramelized onions. Use a large, heavy-bottomed pot to ensure even heat distribution and to allow plenty of room for the onions to cook; otherwise, they’ll steam instead of brown. It’s best not to use a non-stick skillet as flavorful caramelized onions rely on creating a fond, the browned bits of onion that stick to the bottom of the pan. Caramelize the onions for 20 to 25 minutes over medium-low heat, stirring occasionally, until they are blonde in color and retain a bit of their bite. For more information, check out our primer How to Caramelize Onions.

Cheese On French Onion Soup

French onion soup is traditionally topped with golden, buttery Gruyère, an excellent melting cheese from Switzerland. Substitutes for Gruyère include Comté, Jarlsberg, Emmental or Fontina. You can also use a combination of two or more cheeses for French onion soup, including varieties of Swiss, Parmesan, mozzarella or Provolone.

What to Serve with French Onion Soup

To make it a full meal, serve French onion soup with simple salads and bright dressings to cut the soup’s richness, such as Tyler’s Arugula Salad and Ultimate Vinaigrette or Pomegranate, Arugula Salad, along with extra baguette for dipping and mopping up the soup broth.