How to Make French Onion Soup

Golden caramelized onions in a savory broth topped with crusty bread and gooey melted cheese—it’s hard to imagine anything more warm and inviting than a crock of French onion soup.

Slightly sweet, a little salty, and filled with flavor, this soup takes some time to make but is easy to pull off. The time-consuming part comes in waiting for the onions to properly caramelize, but the wait is worth it.

You can make this soup using a handful of traditional ingredients or experiment to your liking. Let’s dive in to how to make French onion soup!

The Origins: What Is French Onion Soup?

The soup’s name comes from its twist on onion soup rather than the name of a specific onion. It’s difficult to pin down French onion soup’s origins; onion soup has been around for thousands of years, but the distinction that makes it French seems to come from the use of beef stock and yellow onions, and the use of butter instead of olive oil.

Gruyere cheese, a French cheese that’s typically pricier, also gave the soup a little snob appeal and nudged it beyond its association with a vegetable eaten by commoners or peasants.

Today’s versions include a variety of alternative (and equally delicious) ingredients enjoyed by everyone, but if you’re a traditionalist, look for recipes with those base ingredients. French onion soup is also traditionally served in a crock, which is oven-safe, deep enough to provide a good ratio of soup to bread, and often has handles—giving you something to hold onto as you dig into the bread and cheese.

Standard Ingredients and Variations

French onion soup is a dish of caramelized onions in a broth that’s topped with bread or croutons and cheese, then put under a broiler to brown the top.

The ingredients include:

Onions

Yellow onions are the traditional choice, but you can also use white or red.

Broth or Stock

Traditional recipes call for beef stock, but you can substitute chicken or vegetable stock (particularly if you want to make it vegetarian). If you do substitute, consider what seasonings or other ingredients you may need to round out the flavor. Some chefs will also use beef consomme, a clarified beef broth that’s rich in flavor.

Butter

Most recipes call for butter, though some use olive oil or a combination of butter and olive oil.

White Wine

Most recipes call for white wine to deglaze the pan when caramelizing the onions and then making the broth, and many call for a second liquor as well. Julia Child used white wine and cognac, many chefs use dry sherry, and chef Alton Brown uses apple cider.

Bread

French bread or croutons are the standard choice here. You’ll need a good crusty bread, but not such a hard crust that you need to use a lot of force and splash into your soup. Some enterprising home cooks make a grilled cheese on the side and then top their French onion soup with that.

Cheese

The traditional choice is gruyere, though many recipes call for a blend of cheese. Swiss, gouda, asiago, and parmesan are all good choices—anything that melts and browns well.

Seasonings and Other Twists

Some people like to add a bay leaf, thyme, pepper, a little garlic, or other spices and seasonings. Other twists include a dash of worcestershire sauce. Others have been known to add mushrooms, which sounds delicious but begs the question of whether it’s still French onion soup.

Putting it all Together: French Onion Soup Recipe

You will need:

2 lb yellow onion, thinly sliced
1.5 oz butter, clarified
¾ qt veal stock
¾ qt chicken stock
1/8 oz thyme
1 ½ oz sherry
4 slices of baguette bread
6 oz gruyere cheese

To combine, follow these steps:

Saute the onions in the butter over low heat. Carefully caramelize the onion without burning. This can take up to 45 minutes.
Deglaze the pan with 8 ounces of the beef stock. Cook au sec. Repeat this process until the onions are a very dark, even brown.
Add the remaining beef stock, the chicken stock and the thyme.
Bring to a simmer and cook 20 minutes to develop flavor. Adjust the seasoning and add the sherry.
Serve in warmed bowls. Top each portion with a slice of toasted French bread and a thick layer of gruyere. Place under the broiler or salamander until the cheese is melted and lightly browned.

You can store French onion soup in the fridge or even freeze it, but make sure you’re only saving the soup and haven’t topped it with the bread or cheese. When you’re ready to serve, reheat the soup on the stove and repeat step 5.

Tips for French Onion Soup Success

Caramelizing the Onions

When you caramelize onions, you cook them for a long time over low heat so their sugars release and … caramelize. This produces a dark brown color and sweet flavor.

Peel and slice the onions thin, melt butter in a large pot (like a Dutch oven), and then put the onions in the top and stir regularly over medium heat. Make sure the onions don’t burn. You’ll wind up with brown bits at the bottom of the pan but the onions should be soft. This step can take as long as an hour.

Adding Broth and Wine at the Right Time

When the onions are ready, they’ll be soft and nearly translucent. That’s when you add your broth and wine, bring the mix to a boil, and then reduce the heat and let it simmer for 20 or 30 minutes. Add these components too soon, and you won’t have as much to deglaze.

Deglazing

Warm up your choice of stock or broth in a separate pan. You’ll use some of this broth to deglaze the pot with the onions, adding some liquid to free up those yummy brown bits and to keep the onions from burning, then add the rest for the third step.

Nailing the Soup-to-Bread Ratio

As you ladle the soup into individual crock pots or ramekins, you’ll want to leave enough space for your crusty bread and choice of cheese without overfilling. Take a look at how thick your bread is and leave about that much room from the rim of the ramekin. The bread will sink a little into the broth, creating a nice indentation in which the cheese will sit as it melts.

What to Serve with French Onion Soup

French onion soup is often a meal on its own, but if you want a little more, a wide variety of foods pair well with it. Think of any flavors that would complement your choice of cheese and the saltiness of the soup. With all that cheese and bread, you probably don’t want to add something heavy, so also think light.

Some ideas include:

Soup and sandwich, naturally!
A dinner salad or side salad, particularly one with some tart fruit like sliced green apples, pears, or craisins
Grilled vegetables (ratatouille is also a possibility but might be too heavy)
Roast beef—which gives you the flavors of a French dip sandwich

French Culinary Techniques Way Beyond Just Soup

French onion soup is a classic that can impress guests, make for a great comfort food, and is surprisingly easy to make. It’s also versatile and can be fun to experiment with.

Find out more with home gourmet online cooking classes like Classic Soups or Slow Cooker Revolution.

Or, if you want to pursue a culinary education, consider a degree or diploma in culinary or pastry arts. Escoffier offers both on-campus and online options, making it easier for you to find a way to fit school into your life.

Want to know more about soups—and cheese? Try these articles next:

How to Make Wisconsin Cheddar Beer Soup
Cheddar Cheese: An Origin Story
5 Ways to Use Chicken Stock

*This article was originally published on October 29, 2014, and has been updated.

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