French onion soup is a bistro classic for a reason—the combination of deeply savory, onion-packed broth and a cheesy browned crouton makes for a satisfying, comforting dish.
As the crouton sits in the broth, it becomes soft enough to break apart with a spoon, giving you cheesy, bready goodness in every bite.
This pressure cooker version comes together in just over an hour (but if you don’t have an Instant Pot, you can also make Stovetop French Onion Soup).
Even better, it’ll stay hot on your pressure cooker’s warming setting for hours, so you can prepare the soup any time of day that’s convenient, then add the cheesy toasts just before serving.
HOW TO MAKE FRENCH ONION SOUP IN A PRESSURE COOKER
Using your pressure cooker’s high “sauté” setting will speed up caramelizing onions for French onion soup—I find that it takes just half an hour for them to become golden and sticky-sweet.
I like to start by adding salt and sugar to the onions (this helps to draw out their liquid), then leave a lid on the pot for about 10 minutes to really kickstart the sweating process. Instant Pot makes a non-pressure cooking lid, or you can use any 9-inch tempered glass or metal lid from your cabinet.
Then, finish caramelizing the onions with the lid off for another 20 minutes or so, stirring occasionally, until they’re golden brown.
Finally, you’ll add the rest of your ingredients and cook the soup under pressure for five minutes. The pressure cooking softens the onions even further and helps to meld all of the flavors together.
At this point, the soup itself is done—all you need to do is ladle it into bowls; add a slice of bread to each bowl, and broil some cheese on top in the oven.
- New to the Instant Pot? Read our First Timer’s Guide to all things Instant Pot.
THE BEST ONIONS FOR FRENCH ONION SOUP
For the onions, yellow or red ones work equally well. Choose regular onions over the “sweet” varieties, since they’ll tend to have more flavor.
THE BEST BREAD FOR FRENCH ONION SOUP
A French baguette is traditional, but you can try sourdough if you like a tangier flavor. Just make sure the bread is nice and crusty so it can hold up well to being dunked in the soup.
THE BEST CHEESE FOR FRENCH ONION SOUP
Let’s be real—just about any melty cheese is going to be delicious when broiled on top of a crusty slice of bread.
The traditional cheese is Gruyere (and that’s what I’ve used here). Its nutty, slightly sweet taste complements the beefy, oniony broth. If you can’t find Gruyere, use Jarlsberg, Emmental, or any Swiss cheese for a similar substitute. Sharp cheddar would be tasty, too.
WHAT TO SERVE WITH FRENCH ONION SOUP
French onion soup makes a hearty first course for a roast chicken dinner. It’s also great as a light lunch or afternoon snack—either on its own or with some lightly dressed greens (and maybe some more cheesy croutons) on the side.
STORING AND FREEZING FRENCH ONION SOUP
This soup will keep for about five days in the fridge. To reheat, warm the soup on the stovetop or in the microwave, then top with bread and cheese, and broil before serving.
If you’d like to make ahead and freeze your French onion soup, freeze the soup separately from the bread and cheese.
My favorite method for freezing is to place a silicone mini-loaf pan on a baking sheet, ladle portions of soup into the pan, let them freeze solid, then pop out the “loaves” of soup into a freezer-safe bag or other container. They’ll thaw faster than if you froze the soup in a big block, and you can reheat them in a pot on the stovetop or in individual servings in a microwave-safe bowl.
NEED MORE SOUP RECIPES?
Instant Pot French Onion Soup Recipe
If you don’t have broiler-safe bowls, you can toast the cheesy bread separately, then add one slice to each bowl of soup just before serving.
For the soup:
- 1/4 cup unsalted butter or vegetable oil
- 2 1/2 to 3 pounds yellow or red onions, halved, peeled, and sliced 1/4-inch thick
- 1 tablespoon brown sugar
- 1 1/2 teaspoons kosher salt
- 1/4 cup dry sherry or vermouth
- 4 cups low sodium beef broth
- 1 teaspoon Worcestershire sauce
- 1/4 teaspoon ground black pepper
- 1/4 teaspoon dried thyme leaves or 1 teaspoon fresh thyme leaves
- 1 bay leaf
For the toasts:
- 6 (1-inch thick) slices of a baguette
- 1 1/4 teaspoons Dijon mustard
- 1 cup grated Gruyere cheese
- Freshly ground black pepper
1 Set the cooking time: Select the high sauté setting on your pressure cooker. If it’s an Instant Pot or similar model, the timer should default to a cooking time of 30 minutes. You will use every minute of this to sauté the onions.
2 Add the fat and caramelize the onions: Add the butter or oil to the pressure cooker. Once the butter has melted or the oil shimmers, about 2 minutes, add the onions, sugar, and salt and stir with a wooden spoon, separating the onion layers and coating the slices with the fat.
Cover the pot with a tempered glass lid or other 9-inch pot lid and let the onions cook, without stirring, for 10 minutes.
3 Uncover the pot and continue cooking the onions: Uncover the pot. At this point the onions should be softened, but not brown, and there should be some liquid at the bottom of the pot.
While wearing an oven mitt, hold the rim of the inner pot in place, and stir the onions vigorously. Be careful not to splash hot liquid on yourself.
Continue to stir the onions vigorously every 2 minutes, making sure to nudge loose any fond or brown bits from the bottom of the pot as it develops with your spoon. Do this until the sauté cooking program has ended after 30 minutes and the pot turns off automatically.
At this point, the onions should be caramelized and golden brown.
3 Deglaze the pot and cook the soup under pressure: While the pot is off but still hot and the onions are sizzling, add the sherry. Use a wooden spoon to thoroughly scrape any remaining fond from the pot bottom.
Stir in the broth, Worcestershire, thyme, bay leaf, and pepper. Secure the pressure cooker lid in its sealing position, then select the manual setting, and set the time for 5 minutes at high pressure.
(The pot will take about 10 minutes to come up to pressure before the cooking program begins.)
4 Release the pressure and prepare to serve: When the cooking program ends, let the pressure release naturally for at least 15 minutes, then move the pressure release valve to "venting" to release any remaining steam.
At this point, the soup will stay hot on the “keep warm” setting for up to 10 hours, until you are ready to serve it.
When you are ready to serve the soup, discard the bay leaf. Taste the soup for seasoning, adding salt and/or pepper if needed.
5 Make the toasts and finish the soup: Preheat the broiler on your oven and line a baking sheet with aluminum foil. Place broiler-safe serving bowls on the baking sheet, then ladle the soup into the bowls, filling them to about 1/2-inch from the top.
Spread the baguette slices very sparingly with Dijon mustard (1/4 teaspoon per slice), then place the baguette slices on top of the bowls of soup.
Heap a pile of the Gruyere cheese onto each baguette slice. Grind one or two grinds of black pepper on top of each slice. Broil for 3-5 minutes, or until the cheese is bubbly and beginning to brown.
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