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Vegetarian french onion soup with red wine croutons

2013 January 14

One of my very favorite things to do on a dreary winter afternoon — the kind of day where you curl up on the couch with a cup of tea and watch reruns of Downton Abbey — is to set something on the stove that will simmer for hours and scent the house with an irresistibly warm, tummy-rumbling fragrance.

Soup does that. Quite well, in fact. In my household, there’s just something about the scent of onion soup that puts everyone in a good mood. Rich and savory — yes, even the vegetarian version — and capped with crunchy croutons and Gruyere, it’s a full, satisfying meal on a cold January day.

The secret to vegetarian french onion soup is, not surprisingly, onions. Lots and lots of onions, caramelized to within an inch of their lives. Prepare to put your knife skills to work — a food processor (in my experience, at least) shreds onions into a liquid mess.

I find slicing onions to be quite relaxing, truthfully — there’s a method to the madness that makes it move along quickly and keeps the eye-burning to a minimum. Here’s a short primer:

  • Slice off the stem end.
  • Set the onion on the newly created flat side, and cut it in half dead center through the root end.
  • Remove the onion peel from both halves.
  • For half moon slices: Set one half on its long flat slide (i.e., the root end is resting on the cutting board, not sticking straight up in the air). Starting at the end opposite the root end, begin making 1/8″ thick vertical slices. Continue down the onion until you reach the root end.
  • For quarter moon slices: Set one half on its long flat slide. Position your knife over the center of the rounded part of the onion, with the tip pointing at the root end. Make a cut straight down — don’t cut through the root end (this will help hold the onion together as you make further slices). Then, at the end opposite the root end, begin making 1/8″ thick vertical slices.

Easy as pie.

So, where’s the beef? you might ask. It’s in the mushrooms. Lovely, lovely, lovely dried porcini mushrooms create a flavorful broth that will leave you asking, Beef? Who needs beef?

(Tip: it’s not part of the recipe, but if you’re making your own mushroom broth, chop up the rehydrated mushrooms and add them to soup for extra texture and mushroomy kick.)

Sauteing croutons in red wine is not so much for flavoring the soup, but rather to add a little extra zing as you work your way through the crusty top to get to the soup below. Red wine croutons, melty Gruyere cheese. You can see where I’m going with this.

After an afternoon with the deeply savory scent of onions, you’ll want to end the evening on a bright, fresh note:

Set a small pot with about 2 cups of water to boil. Add 2 or 3 large strips of lemon and/or orange zest, 1 small cinnamon stick, 5 or 6 whole cloves, 5 or 6 allspice berries, and 1 teaspoon of vanilla extract. Reduce heat to maintain the barest simmer. Check the pot every hour to ensure it hasn’t boiled dry, adding more water as necessary.

Vegetarian french onion soup with red wine croutons

technique adapted from Cooks Illustrated

A long, slow simmer in the oven ensures the onions are caramelized – not burned – which can easily happen on the stove-top.


  • for the soup:
  • 2 tablespoons neutral, medium-heat oil (like grapeseed oil)
  • 7-8 medium yellow onions (about 5-6 pounds), thinly sliced into half or quarter moons
  • 1/3 cup dry sherry
  • 4 cups vegetable broth
  • 1 cup mushroom broth*
  • 1 cup water
  • 3 sprigs fresh thyme
  • 1 bay leaf
  • salt and freshly ground black pepper
  • for the croutons:
  • 1 tablespoon olive oil
  • 2 cloves garlic, smashed and minced
  • 1 small Italian or French loaf (day-old is fine), sliced into 1″ cubes
  • 1/4 cup good red wine
  • Gruyere cheese shavings (about 3 ounces)
  • salt and freshly ground black pepper


  1. Prepare the soup: Preheat oven to 375 deg F. Position rack in the center of the oven (you might have to remove the second rack to accommodate a pot with a lid). Meanwhile, heat oil in a 4 to 5 quart dutch oven (on the stove) on medium heat until shimmering. Add the onions along with a big pinch of salt, and stir well to coat with the oil. Cover and simmer for about 15 minutes, until the onions are soft and translucent. (You can also do this part in the oven – it will take 30 to 45 minutes for the onions to reach the soft stage.)
  2. When the oven finishes preheating, give the onions one final stir and spread them evenly on the pan bottom. Set the lid askew on the pot, and place in the oven. The onions will need to cook for about 1 1/2 to 2 hours. Check after 45 minutes, giving everything a good stir, resetting the lid again askew. Begin checking the onions about every 10 minutes at the 1:20 hour mark – you don’t want the onions to burn, but if they’re deeply golden brown with some burnt bits stuck to the bottom, they’re ready.
  3. Remove the pot from the oven, and immediately place on stove on medium heat. Add 1/4 cup water and begin deglazing the the pan, loosening any baked on bits. Cover and simmer for 10 more minutes.
  4. Pour in the sherry and thoroughly deglaze the pan. Simmer until most of the sherry is evaporated (about 5 minutes). Add the vegetable and mushroom broths, plus the thyme and bay leaf. Reduce heat to medium-low, cover, and simmer for about a half hour.
  5. Prepare the croutons: Heat the olive oil in a saute pan over medium until shimmering. Add the garlic and stir until fragrant. Mix in the bread cubes, stirring to soak up the oil. Saute until the cubes are toasted on all sides. Drizzle the wine evenly over the croutons and heat for a few additional minutes to dry out the cubes just a bit.
  6. Preheat the broiler.
  7. Ladle the soup into broiler-safe bowls. Layer croutons on top. Drape gruyere shavings over the croutons. Set bowls on a rimmed baking sheet and place under broiler. Remove when cheese begins to bubble and turn brown. Serve immediately.
  8. * To make a quick homemade mushroom broth, purchase a 1/2 ounce bag of dried porcini or cremini mushrooms. Empty the bag in to 1 cup of very, very hot water and soak for about 20 minutes. Remove the mushrooms (use for a different purpose), and strain the mushroom broth through cheesecloth or a coffee filter to catch dirt residue.
Prep Time: 20 minutes       Cook time: about 3 hours       Yield: 4 servings
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8 Responses
  1. January 14, 2013

    Gorgeous! French Onion Soup is one of my husband’s favorites, but it’s hard to find a good vegetarian version. Adding some depth to the broth with mushrooms is a great idea.

  2. January 14, 2013

    M y husband loves french onion soup and this recipe looks beautiful and so hearty. Your photographs are beautiful!

    • Karen @ Leaf & Grain permalink*
      January 15, 2013

      Thank you, Jessica!

  3. January 16, 2013

    Yum! The french onion soup looks wonderful, its nice to see a vegetarian version of it! Your pictures are beautiful as well!

  4. Samantha permalink
    March 20, 2013

    This soup turned out amazing! However, I must know where you got that amazingly gorgeous knife…please?

    • Karen @ Leaf & Grain permalink*
      March 20, 2013

      Thank you, so glad you tried it! Most of my props come from open-air flea markets in the summer, but this one, I couldn’t resist on eBay ;) (search for vintage bread knife clauss)

  5. April 20, 2013

    Oh my…my good friend Google led me directly to this recipe and am I ever happy it did! Just delicious, I couldn’t get enough of this soup. It looked beautiful, and tasted devine! Wow!

    I changed a couple things: skipped oven baking the onions since I couldn’t bear to wait three hours; sauteed for 45-1 hour until brown and super sweet; used red wine instead of sherry (because that’s what I had); and made croutons from a baguette. The homemade mushroom stock is such a great idea, offering so much flavour without the salt.

    So, SO good! Thank you, Karen!

  6. May 23, 2013

    Wonderful blog! I found it while surfing around
    on Yahoo News. Do you have any tips on how to get listed in Yahoo News?

    I’ve been trying for a while but I never seem to get there! Cheers

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