France • Regional Dish • Soup
French Onion Soup
Onions cook slowly into a deep broth, then finish under toasted bread and melted cheese for a rich, savory bistro-style soup.
Instructions
- Melt the butter with the olive oil in a heavy pot over medium-low heat. Add the onions and cook for 35 to 45 minutes, stirring often, until deeply golden and very soft. Do not rush this stage. The onions should collapse and caramelize, not scorch.
- Stir in the flour and cook for 1 minute so the soup thickens lightly without tasting pasty.
- Pour in the white wine and scrape the pot well. Let it reduce for 2 minutes.
- Add the beef stock, thyme, bay leaf, salt and pepper. Bring to a gentle simmer and cook, uncovered, for 25 minutes, until the broth deepens and the onions fully soften.
- Meanwhile, toast the baguette slices until crisp and lightly browned.
- Heat the grill or broiler. Ladle the soup into oven-safe bowls. Top each bowl with a baguette slice and a generous layer of cheese.
- Broil for 2 to 4 minutes until the cheese melts, bubbles and browns in spots. Watch closely so it does not burn.
- Rest for 2 minutes before serving. The soup should be hot, the onions fully tender and the cheese topping still molten.
Cultural Context
French onion soup is bistro comfort with a Parisian accent: slow onions, good broth, toasted bread and a cheese cap that knows how to make an entrance. It’s long been treated as a practical winter dish, with roots often traced to 18th-century France. The formula can shift. Stock, alcohol and cheese vary, but the identity stays clear. The onions need time to soften, sweeten and color without scorching. The broth should support them, not drown them in ambition. Then the bread and cheese broil into the soup, not perch sadly on top like a dairy hat. That’s when it becomes the classic.
Fun Fact
The gratinéed version most people picture today became strongly associated with Paris’s Les Halles in the 19th century.
Cook’s Tip
Cook the onions slowly. The broth should support them, not bury them under too many extras.
Trivia
A Paris dining club called the Dîner de la soupe à l’oignon was founded in the 1810s.
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