Classic French Onion Soup Recipe
By Trevor Farias · Updated · 2 hours 5 minutes total · About 10 cups (6 servings)
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In a nutshell
To make French onion soup, cook 3 pounds of thinly sliced yellow onions in butter over medium-low heat for about an hour, until deep golden brown. Add garlic, a splash of white wine, a little flour and 8 cups of beef broth with thyme, then simmer for 30 minutes. Ladle into oven-safe bowls, top with toasted baguette and grated Gruyère, and broil until the cheese bubbles and browns.
French onion soup is proof that patience is an ingredient. There is nothing fancy in the pot, just onions, butter, broth and a little wine, but an hour of slow cooking turns the onions sweet, jammy and deeply savory. Top each bowl with toasted bread and plenty of Gruyère, slide it under the broiler, and you have one of the great comfort foods.
This recipe sticks to the classic bistro version. The only real secret is not to rush the onions. Below you will find how to tell when they are properly caramelized, what to do if they start to stick, and which cheese and bowls to use.
Why this recipe works
- Cooking the onions low and slow for about an hour develops deep, sweet caramel flavor without burning.
- A splash of wine lifts the browned bits from the bottom of the pot, and that is where much of the flavor is.
- A spoonful of flour gives the broth a little body so it is not thin and watery.
- Toasting the bread before it goes on the soup keeps it from turning to mush.
- Gruyère melts smoothly and browns beautifully, with a nutty flavor that suits the sweet onions.
How to caramelize onions for soup
Slice the onions thinly and evenly, from root to tip, so they cook at the same rate. They will fill the pot at first, but they collapse to a fraction of their volume. Cook them in butter over medium heat for the first 10 minutes, stirring often, until they soften and release their liquid. Then turn the heat down to medium-low and let them cook slowly, stirring every 5 minutes or so.
After 45 minutes to an hour, the onions should be soft, sticky and the color of dark honey. If a brown film builds up on the bottom of the pot, add a tablespoon or two of water and scrape it up; that browned layer is flavor, not burning. If the onions look black or smell bitter, the heat is too high.
Which onions and cheese work best?
Ordinary yellow onions are the best choice. They have the right balance of sweetness and sharpness and brown well. Sweet onions such as Vidalia also work, but the soup will be sweeter, so you may want a little more salt or a splash of sherry vinegar at the end.
Gruyère is traditional. Swiss cheese, Comté or Emmental are good substitutes. A little Parmesan sprinkled on top helps it brown.
Do I need special soup bowls?
You need oven-safe bowls or crocks that can go under the broiler. Set them on a rimmed baking sheet so they are easy to move and any cheese that drips over does not land on the oven floor. If you do not have oven-safe bowls, put the cheese toasts on a baking sheet, broil them until bubbling, and float them on top of each bowl of hot soup.
How to store french onion soup
- Refrigerate the soup without the bread and cheese in an airtight container for up to 4 days.
- Freeze the soup for up to 3 months. Thaw overnight in the refrigerator, reheat on the stove, then add fresh toast and cheese and broil.
Variations to try
- Vegetarian: use a rich mushroom or vegetable broth and add 1 tablespoon soy sauce for savory depth.
- Sherry finish: stir 1 to 2 tablespoons of dry sherry into the soup just before serving.
- Slow cooker onions: cook the sliced onions with the butter and salt on low for 10 hours with the lid slightly ajar, then continue on the stove from step 3.
Frequently asked questions
- How long does it take to caramelize onions for French onion soup?
- About 1 hour in total: 10 minutes over medium heat to soften, then 45 minutes to 1 hour over medium-low, stirring regularly, until they are deep golden brown and jammy.
- What is the best cheese for French onion soup?
- Gruyère is the classic choice because it melts smoothly and has a nutty flavor. Swiss, Comté or Emmental work well too. A little Parmesan on top helps it brown.
- Can I make French onion soup without wine?
- Yes. Use an extra 1/2 cup of broth to deglaze the pot, and add 1 to 2 teaspoons of sherry vinegar or apple cider vinegar at the end for brightness.
- Can French onion soup be made ahead?
- Yes, it tastes even better the next day. Make the soup up to 4 days ahead and refrigerate. Reheat it, then add the toast and cheese and broil just before serving.
Recipe card
Classic French Onion Soup Recipe
Classic French onion soup with slowly caramelized onions, rich beef broth and a bubbling Gruyère cheese toast on top. How to caramelize onions without burning them.
By Trevor Farias · Updated
- Prep
- 20 minutes
- Cook
- 1 hour 45 minutes
- Total
- 2 hours 5 minutes
- Makes
- About 10 cups (6 servings)
Ingredients
For the soup
For the topping
Equipment
- Large Dutch oven or heavy soup pot
- Sharp knife and cutting board
- Wooden spoon
- 6 oven-safe soup bowls or crocks
- Rimmed baking sheet
Instructions
Start the onions
Melt the butter with the olive oil in a large Dutch oven or heavy soup pot over medium heat. Add the sliced onions and salt and stir to coat. Cook, stirring often, for about 10 minutes, until the onions soften and collapse.
Caramelize slowly
Turn the heat down to medium-low. Cook for 45 minutes to 1 hour, stirring every 5 minutes, until the onions are soft, sticky and deep golden brown. If the bottom of the pot starts to brown too much, add 1 to 2 tablespoons of water and scrape it up.
Tip: Do not rush this step. The color of the onions becomes the color and flavor of the soup.
Add garlic, wine and flour
Stir in the garlic and cook for 1 minute. Pour in the wine and scrape up all the browned bits from the bottom of the pot. Let it bubble until almost evaporated, about 2 minutes. Sprinkle in the flour and stir for 1 minute.
Simmer the soup
Gradually stir in the beef broth. Add the thyme, bay leaf and pepper. Bring to a boil, then reduce the heat and simmer, partly covered, for 30 minutes. Remove the thyme stems and bay leaf. Taste and add salt as needed.
Toast the bread
While the soup simmers, heat the oven to 400°F. Lay the baguette slices on a baking sheet and toast for 8 to 10 minutes, turning once, until dry and lightly golden.
Broil and serve
Switch the oven to broil. Set 6 oven-safe bowls on a rimmed baking sheet and ladle in the hot soup. Top each with 2 toasts, then cover generously with Gruyère and a sprinkle of Parmesan. Broil 6 inches from the heat for 3 to 5 minutes, until the cheese is bubbling and browned in spots. Serve carefully; the bowls will be very hot.
Notes
- Allow a full hour for the onions; this is where the flavor comes from.
- Use low-sodium broth so you can control the salt.
- Set the bowls on a baking sheet before broiling for safe handling.
Nutrition (per serving, estimated)
| Calories | 430 |
|---|---|
| Fat | 22 g |
| Saturated fat | 12 g |
| Carbohydrates | 36 g |
| Fiber | 4 g |
| Sugar | 12 g |
| Protein | 21 g |
| Sodium | 1150 mg |
| Cholesterol | 60 mg |
Serving size: 1 of 6. Nutrition is calculated from standard ingredient data and will vary with brands and substitutions.
Recipe from Trevor's Kitchen · https://trevorfarias.com/recipes/french-onion-soup
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