French Onion Soup
Deeply caramelized onions simmered in a rich broth, ladled into bowls and topped with a toasted slice of bread and bubbling, golden Gruyère.
Onion soup has fed people in France since the Middle Ages, when onions were among the cheapest and most plentiful vegetables. The gratinéed version, topped with toast and melted cheese, became famous in the bistros around Les Halles, the old central market in Paris, where it was served to market workers and late-night revelers. It needs few ingredients, but it does need patience: the onions must cook slowly until they are deep brown and jammy.
Why this recipe works
- Really caramelized onions. Cooking the onions low and slow for about an hour turns their sugars deep brown and gives the soup its sweet, rich flavor. There is no shortcut that tastes the same.
- Deglazing. Splashes of liquid lift the dark film that forms on the bottom of the pot back into the onions. That fond is pure flavor.
- A good broth. Use the best beef broth you can find, or a mix of beef and chicken broth for a lighter flavor.
- Gruyère. This Swiss cheese melts smoothly and browns beautifully, with a nutty flavor.
How to caramelize onions
Slice the onions evenly from root to tip so they hold their shape. Start them covered over medium heat to soften, then uncover and cook over medium-low, stirring every few minutes. If they start to stick and darken too quickly, add a tablespoon of water and scrape the pot. They are ready when they are a deep chestnut brown.
FAQ
Do I need oven-safe bowls?
For the classic bubbling top, yes. Without them, place the cheese-topped toasts on a baking sheet under the broiler until melted and float them on the soup.
Can I make it ahead?
The soup keeps well for 4 days; add the toasts and cheese just before serving. For another soup with a story, try our Hungarian goulash.
French Onion Soup
Ingredients
For the soup
For the topping
Conversions are rounded for convenience. For baking, use the original measurements where possible.
Instructions
Caramelize the onions
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Melt the butter in a large Dutch oven over medium heat. Add the onions and salt, cover and cook for 15 minutes, stirring occasionally, until soft and wilted.
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Uncover, add the sugar and reduce the heat to medium-low. Cook for 45 to 60 minutes, stirring every few minutes and scraping the bottom, until the onions are deep golden brown and jammy. Add a splash of water whenever the bottom of the pot starts to darken.
Make the soup
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Add the garlic and cook for 1 minute. Sprinkle in the flour and stir for 1 minute.
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Pour in the wine and scrape up the browned bits. Simmer for 2 minutes.
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Add the broth, thyme, bay leaf, Worcestershire sauce and pepper. Bring to a boil, then simmer gently for 25 to 30 minutes. Remove the herbs and taste for salt.
Gratinée
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Heat the broiler (grill). Toast the baguette slices on a baking sheet until golden on both sides.
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Set six oven-safe bowls on a baking sheet and ladle in the hot soup. Top each with a toast and a generous handful of Gruyère.
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Broil for 2 to 4 minutes, until the cheese is melted, bubbling and browned in spots. Serve carefully; the bowls will be very hot.
Notes
- Yellow onions give the best balance of sweetness and depth. Sweet onions can make the soup too sweet.
Tips
- A splash of brandy or dry sherry stirred in at the end adds warmth and complexity.
Substitutions
- Wine: replace with extra broth and 1 tbsp sherry vinegar or red wine vinegar.
- Cheese: Comté, Emmental or Swiss cheese all melt well.
- Vegetarian: use a rich mushroom broth and vegetarian Worcestershire sauce.
Storage and reheating
- Refrigerate the soup without the topping for up to 4 days.
- Freeze for up to 3 months.
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