Make Ahead

Slow-Cooker French Onion Soup

February 17, 2010
2 Ratings
  • Cook time 4 minutes
  • Makes 6 quarts
Author Notes

This soup comes from trial and error, with some inspiration from Julia Child and Nigella Lawson. The amounts are all approximate---you can adjust as you see fit. I make this whenever beef ribs go on sale (you can use other bony cuts, but the tenderness and succulence of shortribs makes this a real treat): I put the meat to roast in the morning, add some water around midday, and then make the onions and croutons closer to dinner time, but the slow-cooker times are very flexible so you could easily adjust (put the meat on when you get home at night, add the water when you go to bed, leave it to cool while you're at work, or let it keep simmering all day). You can also make the broth ahead of time, and freeze all or part of it (and reduce the caramelized-onion volume accordingly). If you're planning to freeze the broth, (1) use less water (or more meat, herbs, and garlic---but same amt of onions) and cook it longer, so you'll have a more concentrated broth and thus need less space in your freezer; and (2) silicone bakeware (either small loaf or muffin shaped) makes for handy freezing molds---you might want a small baking sheet under the loaf/muffin pan it level---unmold the frozen broth into ziploc bags, and thaw as needed. —ody

What You'll Need
  • Broth
  • 2-3 pounds Bone-in beef ribs
  • 1-2 large onions, sliced in 1/4 inch discs
  • 10 cloves garlic, peeled
  • 5 bay leaves
  • 1-2 tablespoons dried thyme, OR 5 springs fresh
  • 2 teaspoons kosher salt
  • 4 whole peppercorns (optional---if using ground pepper, wait until end of cooking to add)
  • 4 quarts water
  • 1-2 teaspoons Braggs Liquid Aminos, or more to taste
  • Onions & Croutons Gratinés
  • 5-6 cups chopped onions
  • 1.5 tablespoons butter
  • 1 tablespoon dried thyme
  • 1 loaf french bread
  • 1/4 pound Swiss cheese (Gruyère, Comté, Emmental)
  1. Broth
  2. Line bottom of slow cooker crock with one layer of solid onion slices (i.e. slice the onions into 1/4 inch discs but don't separate the layers).
  3. Sprinkle garlic, thyme, peppercorns, and bay leaves over onions.
  4. Lay beef ribs on top of everything else (leave some space between each rib) and generously sprinkle with salt.
  5. Put the lid on the slow cooker and set it to "high"; cook for 3-4 hours.
  6. Add water to within 1 inch of top of crock (adding water that's already hot will speed cooking time); cook another 4-8 hours (the longer it cooks, the tastier the broth will be).
  7. Skim fat (or use for croutons gratinés: see below) and add the ground pepper, if using, and Braggs to taste. (I highly recommend the richness of Braggs, but you can also substitute 1 tsp soy sauce or 2 tsps kosher salt, or more to taste.)
  8. For hearty, chunky soup: fish out rib bones and as many bay leaves as you can find. For more refined soup: strain broth, recovering as much of the meat and garlic as you can pick out.
  1. Onions & Croutons Gratinés
  2. Put butter in a large, heavy skillet over medium heat until just melted.
  3. Stir in onions and thyme.
  4. Set kitchen timer to 8 minutes. Leave the kitchen, returning every 8 minutes to stir the onions, until they've started to caramelize. This should take 45 minutes to an hour: if you get brown patches in your skillet in the first 30 minutes of cooking, turn the heat down. After the onions start caramelizing (at or beyond the 45-minute mark), you may wish to cook them an extra 10-15 minutes, stirring more frequently (every 1-2 minutes), for a sweeter caramel flavor.
  5. Once onions are cooked to your taste, turn off the heat and deglaze the pan with a ladleful of broth.
  6. Make the croutons: Preheat oven to 400 degrees. Line a baking sheet with foil.
  7. Slice bread and cheese. (I like 1/2 inch slices of bread and 1/8 inch slices of cheese, but it's really up to you.)
  8. (Optional) paint bread with extra fat from broth. I dip my brush into the fat that's floating in the crock, and then stir any remaining fat right back into the soup.
  9. Arrange fat-brushed bread cut side down on foil-lined baking sheet and bake for 3-5 minutes, until bread is nicely browned. (The browner it gets, the crispier it'll stay once it gets into the soup.)
  10. Pull sheet out of oven, flip pieces of bread, and lay a slice of cheese on each piece.
  11. Bake for another 5-10 minutes, until cheese is fully melted and just beginning to brown. Remove from oven.
  12. Put it all together: Add onions to crock or broth to skillet, whichever makes the most sense in your kitchen. Put 1 or 2 croutons in each bowl and ladle in the soup. Serve with a big green salad.

See what other Food52ers are saying.

  • AntoniaJames
  • ody

5 Reviews

AntoniaJames March 3, 2010
P.S. The idea of brushing the bread with the beef fat is brilliant. I can't think of a better way to add a rich, gorgeous flavor in this context. Bravo!!
ody March 20, 2010
Yay, I'm so glad you liked it---brushing the fat on the bread also makes it stay crunchier in the soup. Thanks for the detailed review!
AntoniaJames March 3, 2010
For some reason, I can't reply directly to your question . . . the soup was terrific!! I used "English short ribs" and sweet Maui onions, and fresh thyme. Actually I used lemon thyme, because my bush is in a growth period now, and my regular thyme has been heavily used. I also added a couple tablespoons of Worcestershire sauce, because I love its taste with any beef/onion combination. The basic recipe is excellent, and could be used for a nice vegetable beef soup, a hearty minestrone, or a tasty beef and barley soup. Very well done, Ody!
AntoniaJames February 20, 2010
Nice recipe! I plan to make this tomorrow. I especially appreciate all the tips, both in the introduction and throughout the recipe. Very nicely done. Thank you! ;o)
ody March 3, 2010
How did it go??