French onion soup is a Parisian gastronomic classic that combines the sweetness of caramelized onions with the depth of a well-built broth. Its secret lies in time and patience to achieve that deep amber color and unmatched flavor. Perfect for cold nights, this vegetarian version keeps all the traditional character without sacrificing richness.
Ingredients
How many are you cooking for?
Original recipe for 4 servings
- 1 kg yellow onions sliced thinly
- 40 g butter
- 2 tbsp olive oil
- 1 tbsp brown sugar
- 1.5 l vegetable broth
- 200 ml dry white wine
- 8 toasted baguette slices
- 250 g grated gruyere cheese
- salt and black pepper to taste
- 1 bay leaf
Step by step
Follow the timeline: technique icon, time and temperature when relevant.
- Step 1 Pan 25 min
Sauté the thinly sliced onions with butter and olive oil over medium-low heat for 25 minutes, stirring every 5 minutes to prevent burning. The trick is patience: slow caramelization releases natural sugars without bitterness.
- Step 2 Pot / simmer 15 min
Add brown sugar and white wine, scraping the pot bottom to lift the fond. Let the alcohol evaporate for 3 minutes, then slowly pour in the hot broth. This deglazes and concentrates the base flavor.
- Step 3 Pot / simmer 15 min
Season with salt, freshly ground black pepper, and the bay leaf. Partially cover and simmer on very low heat for 15 minutes. Gentle heat allows aromas to meld without evaporating the broth. Remove the bay leaf before serving.
- Step 4 Prep
Ladle the hot soup into oven-safe crocks or porcelain dishes, leaving 1 cm empty at the rim. Wipe the outer surface with a dry cloth to prevent grease stains during broiling. Crocks distribute heat evenly.
- Step 5 Assemble
Place a toasted baguette slice on each crock and sprinkle 30 grams of grated gruyere cheese over the top. Ensure the bread is fully covered so it melts into an elastic crust. Semi-hard cheese provides the classic texture.
- Step 6 Oven 7 min 220 °C
Place the crocks on the upper oven rack and activate the broiler at 220 °C for 5-7 minutes. Watch closely so the cheese browns without burning. High heat creates the signature crunch and bubbling effect.
- Step 7 Serve 2 min
Remove from the oven and let the soup rest for 2 minutes before serving. Use a wooden board as a base to protect your table. Resting allows the cheese to settle and residual heat to finish the melting process.