Soupe à l'Oignon Gratinée (Parisian French Onion Soup) (2024)

This traditional French Onion Soup recipe comes directly from Paris! It's a recreation of the classic served at Au Père Louis, a beloved Parisian bistro in Le Quartier Latin, or Latin Quarter, known to have some of the best soupe à l'oignon gratinée in Paris.

(This recipe was originally published in June 2019, but was updated with new photos and content in 2020).

I have been making classic soupe à l'oignon gratinée for over 2 decades, evolving my process through years of testing and tasting. During a trip to Paris, I sampled what some consider the best French onion soup in Paris at Au Père Louis!

I spoke with who I'm guessing is the owner, and he explained the basic steps to their recipe. He provided no measurements or specifics, but I took copious notes on the method of prep, and decided to attempt this Parisian-inspired recipe upon my return to the States.

The final result is nearly identical to the soup I remember, making this the best outside of Paris too. It's très magnifique! Bon appetit!

Ingredient notes

There are many variables in a seemingly simple onion soup, but it is not a complicated recipe. Most ingredients are readily available and easily accessible. Although there are countless variations for a traditional French onion soup recipe, I find that these are the ideal ingredients for the best results.

• Oil: While some recipes call for butter, the chefs at Au Père Louis (and now I) use plain, neutral-flavored oil, like a vegetable or sunflower oil.
• Onions: You don’t need fancy (sweet) onions. Plain brown or yellow onions will do just fine. That’s actually what Julia Child used too! And don’t skimp. You’ll need a lot of onions (2 ½ pounds) to make this soup properly. Slice them into ¼-inch thick half moons.
• Garlic: Thinly slice your garlic cloves Goodfellas style.
• Flour: This acts as a slight thickener, although it's sometimes omitted in other onion soup recipes. I have always felt that adding flour gives the soup a bit more body, so I include it, as they do at Au Père Louis.
• Wine: There are different camps on what type of wine to use. This recipe uses a small amount of port or Madeira wine to add a little sweetness.
• Broth or Stock: Use good quality homemade or store-bought beef broth or stock. If you don’t have time to make homemade broth, try this beef broth concentrate. I highly recommend it for supreme convenience. You can also make this soup with a combination of beef and chicken broth (or all chicken) for a slightly less umami soup, though it’s not as traditional as all beef.
• Croutons: Cubed baguette is really essential here to get the perfect croutons for your soup. I have tried making croutons for this soup with other crusty breads, but the ratio of crust to soft bready interior is best with a baguette because it has so much more crust. Every single crouton should have a bit of crust on it for optimal texture. I may sound nitpicky but TRUST me I've been making it for decades and this is the best way to do it.
• Cheese: The best and most traditional cheese to melt on top of your soupe à l'oignon gratinée is gruyère cheese. It’s a great melting cheese from Switzerland with a slightly nutty taste.

How to make it

Begin by heating neutral-flavored oil in a large pot over medium-high heat. Add the onions and salt and toss to coat evenly with the oil (PHOTO 1). Lower the heat to medium-low, cover and cook, stirring occasionally, sweating the onions until they are softened, about 15 minutes (PHOTO 2).

Remove the lid and continue to cook uncovered, stirring occasionally another 15 to 20 minutes until most of the residual moisture has evaporated, but don’t cook long enough to caramelize (PHOTO 3).

Add the garlic and bay leaves and cook for another 3 minutes until fragrant. Stir in the flour and then the port wine (PHOTO 4).

Add hot beef broth and stir to combine. Season with more salt and pepper. Partially cover with a lid and simmer on low for about 45 minutes, stirring occasionally.

Meanwhile, preheat the oven or toaster oven to 375°F. Toss baguette cubes with the olive oil or spray them with olive oil spray, and toast in the oven for about 15 to 20 minutes until golden and crusty. Set aside.

Turn on the broiler in your oven or toaster oven. Divide the soup into 4 oven-proof bowls, top with croutons (about 1 cup per serving), and then finish with 2 to 3 ounces of grated Gruyère cheese per serving.

Make sure to evenly cover all the croutons with cheese or else the croutons could burn a little when you broil. Broil until the cheese is melted, bubbly, and golden.

Please scroll to the bottom of the post for the full recipe (in a printable recipe card) including ingredient amounts and detailed instructions.

How to make homemade beef stock (optional!)

Making beef stock from scratch is easier than you'd think, but it’s time consuming. That's the reason most people look for shortcuts. If you choose to make your own stock, I applaud you. If you don't, no judgement.

I have often made this soup with canned broth or beef broth concentrate. It's honestly delicious no matter what! This is just a touch more homemade than the alternative.

First you'll want to roast beef bones with roughly chopped onion. celery, and carrots (PHOTOS 1-2).

Carefully transfer the roasted bones and vegetables to a large stockpot. Deglaze the sheet pan with some white wine (as recommended by the staff at Au Père Louis) and water, and then pour that into the pot.

Top with more water, and then heat until simmering. You do not want to boil your stock, just cook gently. Beef stock will simmer for hours. Skim the impurities off the surface periodically (PHOTO 3).

When the stock has reduced to your liking, carefully strain it and set it aside until you're ready to use it.

One of the magical things about homemade beef stock is that it's quite gelatinous (PHOTO 4)! When you cool your stock, it will look just like Jell-O. This is from the natural collagen in the bones. When you heat the stock again, it will dissolve back into a liquid.

See Also

Campbell's Homestyle Soup, Chicken Noodle SoupCampbell's Classic Chicken Noodle SoupMaison blanche district - activities

Expert tips and FAQs

Following my conversation at Au Père Louis, here are the main takeaways which I have utilized in this recipe:

1. Use homemade stock/broth if possible
2. Reduce, reduce, reduce the stock
3. Slice the onions thicker, cook them in oil, but don't caramelize
4. Add sliced garlic, bay leaf, dusting of flour, port wine, then stock
5. Reduce, reduce, reduce
6. Season generously, especially black pepper!
7. Use smaller croutons (as opposed to toasted baguette slices floating on top)

The recipe I learned in Paris actually breaks one of the cardinal rules in French onion soup making!

Essentially every recipe for traditional French onion soup stipulates caramelizing the onions, sometimes for a full hour. The gentleman at Au Père Louis told me to cook the onions in oil until they are nice and soft, but specified NOT until they are caramelized. He was pretty adamant about that.

In lieu of caramelizing the onions, we add some sweet, fortified wine. At Au Père Louis they use port wine. I use Madeira. Both varieties are significantly sweeter than a run of the mill red wine. This explains why it’s unnecessary to caramelize the onions. Doing so would yield an overly sweet soup.

Many recipes top the soup with toasted baguette slices. I have done this too over the years, but find the smaller croutons SO MUCH EASIER to enjoy in my French onion soup! To get the perfect croutons, cut each slice of baguette in half and then into thirds to yield the perfect size cubes with the perfect amount of crust.

If you can’t find baguettes where you live, use the crustiest bread you can find and only cube up the edges with crust on them. Ciabatta would be an acceptable substitution as it is also quite crusty.

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