French Onion Soup

French Onion Soup

Onion soup is such a classic, comforting and warm dish. It’s deceptively simple. Onions, stock, bread, and cheese. When you make it right you will know it, but it takes both time and patience to be any good.

There are many recipes out there for what I will call half-assed onion soup that can be made in a couple of hours by sauteing onions and adding sugar until they brown relatively quickly. I’ve tried several variations. This recipe, based on Thomas Keller’s time-consuming method, is the right way to make onion soup. I don’t think there is ever going to be an improvement on this recipe.

It will, however, test your patience. By the time you finish cooking this soup, especially if you opt to make your own Homemade beef stock, you won’t even remember that initial craving you had for it. We’re talking about a serious investment of time.

It also won’t matter, because the soup is so good that you and everyone eating it (up to 3 days later) will be in brothy, cheesy, onion-y heaven.

I don’t make a habit out of cooking things for days. Honestly, when I first tried this recipe, I figured it would be a “I’m glad I did it once” type of thing. But I keep coming back to this one. It’s too good not to make, and the process of cooking it is a pleasure. The sweet smell of slowly caramelizing onions on the stove for hours will have everyone in the house making comments.

Three rules:

  • 1. Use the right bowls. You want a nice, thick, oven safe bowl with a wide belly and narrower opening, so that the cheese can extend over the rim. Part of the delight of onion soup is the way these bowls contain the soup and make the cheese form a crispy crust around the edges.
  • 2. Caramelize the heck out of the onions. That doesn’t mean turn up the heat, it just means wait however long it takes on low. They should be dark brown and sweet, not burned. It could take 4-6 hours on low heat to really do it right. Use good, fresh onions with a lot of moisture so that the onions don’t dry out and start to burn easily.
  • 3. Use real stock. Good dark stock. Homemade beef stock is by far the best option. Dark veal stock, if you have it, can also work but has a much lighter flavor. Very dark chicken stock may be also used. Avoid canned beef broth. If you absolutely must cheat, try to find a quality prepared beef stock at a butcher, whole foods or the like.
French Onion Soup

French Onion Soup




  • 2 bay leaves
  • 12 black peppercorns
  • 6 large sprigs of thyme


  • 8 pounds about 8 large yellow onions
  • 8 tablespoons 1 stick unsalted butter
  • Kosher salt
  • 1 1/2 teaspoons all purpose flour
  • 3 1/2 quarts 14 cups Beef Stock (see Making Stock)
  • Freshly ground black pepper
  • Sherry wine vinegar or white wine/champagne vinegar


  • 1 baguette about 2 1/2 inches in diameter
  • Olive oil
  • Kosher salt

To Finish

  • 6 to 12 slices 1/8 inch thick aged Comte or Emmentaler cheese (at least 4 inches square)
  • 1 1/2 cups grated aged Comte or Emmentaler cheeses or a combination



  • Cut a piece of cheesecloth about 7 inches square. Place the bay leaves, peppercorns, and thyme in the center, bring up the edges, and tie with kitchen twine to form a sachet. You may also use a metal tea-ball or anything that will allow you to remove the aromatics from the finished soup.


  • Cut off the tops and bottoms of the onions, then cut the onions lengthwise in half. Remove the peels and tough outer layers. Cut a V wedge in each one to remove the core and pull out any solid, flat pieces of onion running up from the core. Lay an onion half cut side down on a cutting board with the root end toward you. Note that there are lines on the outside of the onion. Cutting on the lines (with the grain) rather than against them will help the onions soften. Holding the knife on an angle, almost parallel to the board, cut the onion lengthwise into 1/4 inch thick slices. Once you’ve cut past the center of the onion, the knife angle will become awkward: Flip the onion onto its side, toward the knife, and finish slicing it, again along the grain. Separate the slices of onion, trimming away any root sections that are still attached and holding the slices together. Repeat with the remaining onions. (You should have a lot of sliced onions, about 7 quarts.)
  • Melt the butter in a large heavy stockpot over medium heat. Add the onions and 1 tablespoon salt, reduce the heat to low. Cook, stirring every 15 minutes and regulating the heat to keep the mixture bubbling gently, for about 1 hour, or until the onions have wilted and released a lot of liquid. At this point, you can turn up the heat slightly to reduce the liquid, but it is important to continue to cook the onions slowly to develop maximum flavor and keep them from scorching. Continue to stir the onions every 15 minutes, being sure to scrape the bottom and get in the corners of the pot, for about 4 hours more, or until the onions are caramelized throughout and a rich deep brown. (Very dark brown, not burned, sweet and rich in taste.) Keep a closer eye on the onions toward the end of the cooking when the liquid has evaporated. They will burn easily at that stage. (I have “tested” this.) Remove from the heat. (You will need 1 1/2 cups of caramelized onions for the soup; reserve any extra for another use. The onions can be made up to 2 days ahead and refrigerated.)
  • Transfer 1 1/2 cups of the caramelized onions to a 5 quart pot (if they’ve been refrigerated, reheat until hot.) Sift in the flour and cook over medium-high heat, stirring, for 2 to 3 minutes. Add the beef stock and sachet, bring to a simmer, and simmer for about 1 hour, or until the liquid is reduced to 2 1/2 quarts. Season to taste with salt, pepper, and a few drops of vinegar. Go easy on the seasonings, nothing should overpower the sweet onion flavor. Remove from the heat. (It’s best to let the soup sit for a day or so in the fridge to allow the flavors to deepen.)


  • Preheat the broiler. Cut twelve 3/8 inch thick slices from the baguette (reserve the remainder for another use) and place on a baking sheet. Brush the bread lightly on both sides with olive oil and sprinkle lightly with salt. Place under the broiler and toast the first side until golden brown, then turn and brown the second side. Set aside and leave the broiler on.


  • Return the soup to a simmer. Place six flameproof soup tureens, with about 1 1/2 cups capacity on a baking sheet to catch any spills (the soup will bubble up and over the tureens). Add the hot soup to the tureens, filling them within 1/2 inch of the tops. Top each serving with 2 croutons: Lay them on the surface – do not push them into the soup. Lay the slices of cheese over the croutons so that the cheese overlaps the edges of the tureens by about 1/2 inch, Scatter the grated cheese over the sliced cheese, filling in any areas where the sliced cheese is thinner, or it may melt into the soup rather than forming a crust.
  • Place the tureens under the broiler until the cheese bubbles, browns, and forms a thick crust. Eat carefully, the soup and tureens will be very hot.
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