5 Mistakes to Avoid When Making French Onion Soup

published Jan 22, 2015
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(Image credit: Brent Hofacker)

French onion soup is so simple, yet rich, luxurious, and deeply comforting. It’s a bistro classic that combines sweet caramelized onions and rich beef broth, then tops it off with a melty cheese-topped crouton.

The ingredient list may be short and sweet, but preparing this soup takes patience and care. Before you take out the soup pot, scope out these mistakes to ensure your soup is the best it can be.

1. Not caramelizing the onions properly

The caramelized onions are the highlight of this soup. They’re the main attraction! Well, good caramelized onions, that is. They truly make this soup what it is, so take your time. Take care not to cook them over too high heat, or take them off the stove too soon.

→ Follow this tip: Give this process the time and care it deserves. Caramelize the onions slowly and deliberately. Don’t rush them — it’s an easy way to end up with burnt onions. Instead, have patience and expect this to take about an hour. You’ll be rewarded with beautiful, dark, evenly browned onions.

2. Rushing the soup!

There are plenty of soups that you can throw together quickly, but French onion soup is not one of them. By rushing the cooking process of this soup, you’re missing out on a huge amount of flavor.

→ Follow this tip: Time is the key ingredient that makes this classic cafe soup so wonderful. It’s what transforms otherwise basic ingredients into a luxurious, warming meal. Cooking French onion soup happens in two phases — first, slowly and carefully caramelizing the onions, then simmering the broth and browned onions for a long time.

3. Using the wrong pot

Unlike most other soup varieties, the type of pot used to prepare this soup matters. It’s best to stay away from tall, narrow pots, which will crowd the onions. Instead, opt for something wider that gives the onions more room to evenly cook.

→ Follow this tip: Select a pot that’s wider than it is deep, like a deep six-quart sauté pan or even a Dutch oven. The wide surface area gives the onions plenty of space to caramelize, and allows the broth to evaporate and concentrate.

4. Skipping the garnish

And by “garnish” I mean the ubiquitous cheesy-topped crouton that finishes off the soup so perfectly. French onion soup is not complete without a thick slice of toasted bread topped with melted Gruyere! Please, don’t try to serve this soup any other way.

→ Follow this tip: Top your soup with a thick, toasty crouton, brushed with butter, then piled with Gruyere cheese. Place the loaded bowl under the broiler for just a couple minutes, until the cheese is melted and lightly browned around the edges.

5. Using the wrong type of cheese

There are times to experiment, and this is not one of them. Don’t use any old cheese you have laying around — French onion soup demands Gruyere.

→ Follow this tip: To keep this soup in tune with its classic bistro roots, stick with using grated Gruyere cheese. It’s the only way to go! Gruyere cheese is rich, smooth, melts with ease, and provides the ideal complement to the sweet onions and savory broth.

What are your best tips for making French onion soup?