Onion soup, with croutons and melted cheese/Photos by Donna Turner Ruhlman

Onion soup, with croutons and melted cheese/Photos by Donna Turner Ruhlman

Donna wanted to change the banner photo on my Facebook page and it got so many likes and comments that I knew it clearly struck a wintery warmth chord in dreary March. I’ve posted this before and here it is again from, Ruhlman’s Twenty, which looks at 20 key concepts that underlie all of cooking. This key concept is water. This onion soup requires nothing but onions and water for the soup part.

Plan ahead when making the soup because the onions take a long time to cook down, from a few hours to as many as five if you keep the heat very low, though you need to pay attention only at the beginning and the end. Before the onions caramelize, they’ll release copious amounts of water (be sure to taste this liquid!), which must cook off first. You can simmer the onions hard if you want to reduce the cooking time; be sure to tend the pot and stir often, or the onions can stick and burn. You can also caramelize the onions a day or two in advance, and refrigerate them for a quick delicious soup during the week, or even freeze the onions for up to a month. If you do this, the soup can be finished in the time it takes to heat the water and melt the cheese on top.


Traditional French Onion Soup

  • 1 tablespoon butter
  • 7 or 8 Spanish onions (7 to 8 pounds/3.2 to 3.6 kilograms), thinly sliced
  • Kosher salt
  • Freshly ground black pepper
  • 6 to 12 slices of baguette or any country-style bread (it’s best if they cover the width of your serving bowls)
  • 1/3 cup/75 milliliters sherry
  • Red or white wine vinegar (optional)
  • Red wine (optional)
  • 1/2 to 3/4 pound/225 to 340 grams Gruyère or Emmanthaler cheese, grated
  1. Use a large pot, with a capacity of about 7 1/2 quarts/7.1 liters, that will hold all the onions. An enameled cast-iron pot will provide the best surface. Place the pot over medium and melt the butter. Add the onions, sprinkle with 2 teaspoons salt, cover, and cook until the onions have heated through and started to steam. Uncover, reduce the heat to low, and cook, stirring occasionally (you should be able to leave the onions alone for an hour at a stretch once they’ve released their water). Season with several grinds of pepper.
  2. Preheat the oven to 200°F/95°C. Place the bread slices in the oven and let them dry completely (you can leave the slices in the oven indefinitely, as the heat is not high enough to burn them).
  3. When the onions have completely cooked down, the water has cooked off, and the onions have turned amber—this will take several hours—add 6 cups/1.4 liters of water. Raise the heat to high and bring the soup to a simmer, then reduce the heat to low. Add the sherry. Taste and season with salt and pepper as needed. If the soup is too sweet, add some vinegar. If you would like a little more depth, add a splash of red wine. I like the onion-to-liquid ratio with 6 cups of water. But if you’d prefer a slightly more delicate soup, add 1 cup/240 milliliters water.
  4. Preheat the broiler/grill. Portion the soup into bowls, float the bread on top, cover with the cheese, and broil/grill until the cheese is melted and nicely browned. Serve immediately.

Serves 4 to 6


If you liked this post on French onion soup, check out these other links:

© 2013 Michael Ruhlman. Photo © 2013 Donna Turner Ruhlman. All rights reserved.


16 Wonderful responses to “In Love with French Onion Soup”

  • Patrick

    FOS is the best! One of the few soups I look forward to. Not only does it taste amazing, but it’s very photogenic. I also love cooking the onions for so long – creates an incredible smell/flavor.

  • Julie

    I LOVE French onion soup! I made it on Friday and we have a few quarts in the fridge that I’ve been steadily demolishing. Next time I make it, I will do so with water. Usually I use beef stock, but if there’s a way to skip that, I’m on board.

  • Scott Johnston

    While I love this recipe, I have also added 6 cups of homemade beef stock (instead of water) to add some more flavor to the party. It does change the flavors, but sometimes that is what I am looking for.
    Any suggestions/ comments on cooking the onions in a crock pot?

    • Ohiogirl

      Scott, I always prep the onions for this in a crockpot. It’s so easy!

      As I work at home, I start them on high, give a stir in a few hours, then cook a few more hours on high – and they are ready for the next step. If I am making the soup that night, I throw them in a big stockpot, put the heat on medium high and they will finish their cooking and become beautifully caramelized in about 15 minutes. Add the water and proceed.

      If you are not cooking the soup that night, let the onions cool, pack them in the fridge and they will keep for DAYS. Then when you want soup, pull them out, put them in the stockpot and, begin.

      If you will not be near them during the day to check – some of the newer crockpots can run hot – put them on low while you sleep. That way you can stir once in the middle of the night (everyone gets up for a glass of water at least once, yes?) and pack them up before you leave for work. Happy cooking!

  • Ruthy @ omeletta

    French Onion Soup is my definite quick and easy winter meal, but I can’t believe I never thought to freeze caramelized onions. Done and done- thank you for such a handy tip!

  • Cheryl

    Jacques Pepin makes a version using the slowly caramelized onions and homemade chicken stock. He then puts the bread and Gruyere on the bottom, ladles the soup and onions over top then puts a 2nd layer of bread and cheese. You bake it in the oven and it is amazing. Never tried it with just water but what a fabulous idea, especially for my vegetarian clients.

  • former butcher

    Not sure I could do without the depth of flavor that beef stock brings to this soup; but water is worth considering. Also important : burn the cheese! A little anyway.

  • Bob Y

    It’s funny. Here in the desert, its in the 80’s and when I saw your post on onion soup, I thought you were out of your mind (or gone off to Key West.) I know much of the country is in dreary March and enough is enough. But even in the 80’s, I could almost talk myself into making a pot. I’ll turn the A/C up 😉

  • Natalie Luffer Sztern

    Liiving in the land of Recette Soupe à l’oignon gratinée, I am going to risk all the negative backlash of your wonderfully experienced readers and give the condensed version on the fly: yes 1 can of condensed French Onion Soup Campbell in a pot, add with one can beef broth; to taste add; 1 tsp red wine; 1tsp beer. Simmer. Taste and season with more if needed…Take a Baquette day old cut into 1/2 in slices and dry in oven if not stale. Pour soup into French Onion Soup Bowl add the crusty bread slice heap on mix of gruyere and asiago and into broiler to brown and melt…making sure the soup is high enough on the bowl so that when the bread is placed with the cheese it is all mounded a bit over the rim…….The first thing one does when they get this soup is pick off the brown cheese clinging to the sides of the bowl before they dig in…whoosh – feeds 2

  • White

    I occasionally caramelize my onions in the oven if I am unable to throw all my attention to the stove-top “sitting”. The uses of the oven are so often overlooked, and this is a case in point.

  • Bobbymo

    Thank You for the repost. Its cold here, think Im gonna have to put on long pants today and cozy up with an Old Fashion. Rocking the homefront in San Diego with Rulman’s “French “O” Soup” tonight.

  • Mike

    Awesome! French Onion Soup was high on my list of new things to make and you delivered as usual 🙂 I thought it was far more complex than this, so this was a great suprise! I can’t wait. Thanks again, Michael!

  • Sean

    French onion soup could be a death row meal for me. However, as much as I love my copy of Twenty, I have to say that this recipe can only be improved by a healthy splash of stock. I know that takes it outside of it’s peasant food origins, but let’s be honest, if I’m going to great $12-15 worth of cheese on my guests soup, I’m going to go to the extra effort of adding homemade stock. If just for that extra bit of body.

  • jimvj

    What if Spanish onions are not available? Will any sweet onion do?


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