The Unconventional Oil That Will Kick Your French Onion Soup Up A Notch

There's nothing that warms you up better than soup — unless it's soup topped with melted, gooey cheese. French onion soup is a common menu item in the United States, though it might appear on the menu more often in colder months. It usually consists of a baguette submerged in a salty, beef-based broth loaded with caramelized onions. The soup is topped with a layer of gruyère or Swiss cheese, then broiled to brown the cheese and melt it. The type of cheese might vary, depending on the recipe.

There are mixed stories about where French onion soup comes from. According to The Culture Trip, it may have been invented by King Louis XV, or it could have been invented by a chef who happened to prepare it one night for King Louis XV's father-in-law. Regardless, we're glad it's here and more than that, happy that it's actually quite easy to make at home. If you're interested in preparing your own French onion soup, you'll want to make sure you use the proper oil to caramelize the onions.

Making French onion soup at home is easy. For the broth, the most basic ingredients are beef broth and dry sherry, though there are certain additions, such as Worcestershire, that many people like to add to build on that salty flavor. The onions play a major role in this soup, so you'll want to caramelize them properly.

Chef Ludo Lefebvre of Los Angeles' Petit Trois told Food & Wine that yellow onions are the best kind to use for the dish due to their texture and ability to caramelize easily. And to prepare them properly, you'll want to use grapeseed oil. It's less commonly used than other cooking oils, such as olive or canola, but Lefebvre loves it for its high smoke point — this means the onions won't burn easily, which is great if you're making the soup for the first time and aren't familiar with its process. Lefebvre says its neutral taste is a good thing, too.

Anything that's salty and loaded with cheese will probably taste good. Still, there are a few ways you can improve your French onion soup technique. Chef Andy Xu, who is the executive chef of New York City's Odeon, told Thrillist that you should leave the onions to caramelize on their own for the first 10 minutes, rather than stirring them constantly. He also suggests watching how much you season the dish since it already has salty elements, such as cheese. "You want to season it, but a little less than you would for normal soup," he suggests.

Surprisingly, French onion soup is made mostly with household ingredients. One element of the dish is sherry, which is a fortified wine that might not be sitting in your pantry. If that's the case, Wine Spectator says you can substitute "white wine, brandy, or dry vermouth." It's possible to substitute red wine, too, though the outlet notes that it might change the flavor a bit.