Soupe à l'Oignon Gratinée (French Onion Soup)

About This Recipe

Soupe à l'oignon gratinée is the soup that defined the Parisian early-morning bistro — the dish that the porters of Les Halles market ate at 4 a.m. when the meat trucks rolled in, and that fashionable diners ate after long nights at the Folies. It is a simple soup made profound by patience: yellow onions, sliced thinly and cooked in butter for at least 45 minutes (preferably 75) until they collapse into a jam-dark caramel, then deglazed with dry white wine or cognac and topped up with a rich beef broth. The transformation in the oven is the dish's signature: each bowl is crowned with a slice of grilled baguette and a thick blanket of Comté or Gruyère cheese, then run under the broiler until the cheese melts down the sides of the bowl into a crisp, golden crust. Done right, you crack through the cheese crust with a spoon and find sweet, almost-burnt onions in a broth that tastes of caramel, wine, and decades of French kitchen tradition. Done wrong (rushed onions, instant beef stock, cheap cheese), it tastes of nothing.

Ingredients

Serves 4

• 1.5 kgyellow onions (about 6 large), peeled and sliced 4 mm thick
• 60 gunsalted butter
• 2 tbspextra-virgin olive oil
• 1 tspfine sea salt
• 1 tspgranulated sugar
• 3 clovesgarlic, minced
• 2 tbsp00 flour
• 200 mldry white wine (Sauvignon Blanc or dry Vermouth)
• 2 tbspcognac or brandy
• 1.5 Lrich beef broth (homemade preferred)
• 2 sprigsfresh thyme
• 1bay leaf
• 1 tbspWorcestershire sauce
• freshly ground black pepper
• 1baguette (day-old preferred), cut into 1.5 cm thick slices
• 250 gGruyère or Comté, freshly grated

Instructions

1. 1

   Slice the onions

   Halve the onions root-to-tip, peel, and slice 4 mm thick along the grain (not crosswise — slicing with the grain holds shape better during long cooking). You should have about 1.2 kg of sliced onion.

   Wear goggles or chew gum while slicing — both genuinely reduce eye sting.

2. 2

   Begin caramelization

   Melt the butter with the olive oil in a heavy 5 L pot over medium-high. Add the onions, salt and sugar. Stir to coat. Cook uncovered, stirring every 5 minutes, for the first 15 minutes — the onions release water and soften.

3. 3

   Long, slow caramelization

   Reduce heat to medium-low. Continue cooking, stirring every 5–8 minutes and scraping the brown fond from the bottom of the pot, for 45–60 more minutes. The onions go from white → translucent → straw → golden → mahogany. Do not rush.

   If the pot dries too much, add a tablespoon of water and scrape — the fond is flavor.

4. 4

   Add aromatics

   When the onions are deep mahogany and jam-like (taste — they should be sweet and almost gummy), stir in the garlic and cook 1 minute. Sprinkle in the flour and cook another 2 minutes, stirring constantly, to cook out the raw flour taste.

5. 5

   Deglaze

   Pour in the white wine and cognac. Scrape the bottom and sides of the pot. Boil hard 3 minutes until the alcohol smell mellows and the liquid reduces by half.

6. 6

   Build the soup

   Add the beef broth, thyme, bay leaf and Worcestershire. Bring to a steady simmer and cook uncovered 30 minutes, allowing the broth to reduce and intensify. Taste for salt — broth quality varies, so adjust. Add black pepper generously.

7. 7

   Toast the bread

   While the soup simmers, lay baguette slices on a sheet pan and toast under a hot broiler 90 seconds per side until golden and crisp. Rub each slice with a halved garlic clove if you like.

8. 8

   Gratinée

   Ladle the soup into 4 oven-safe onion soup bowls (lion's-head ceramic bowls are traditional). Float 1–2 toasted bread slices on top — they should cover the surface. Mound 50–60 g grated cheese over each bowl, letting it hang over the edge slightly.

9. 9

   Broil

   Place the bowls on a sheet pan and broil 8–10 cm from the element until the cheese is bubbling, browned in patches, and crisping over the rim — about 4 minutes. Watch closely; cheese goes from perfect to burnt in seconds.

10. 10

    Serve hot

    Carry the bowls to the table on plates — they're scorching. Each diner cracks through the cheese crust with a spoon to reach the soup beneath. A glass of dry white wine and nothing else is the right meal.

Variations

• •

  Soupe à l'oignon gratinée à la Lyonnaise — adds an egg yolk and a splash of port stirred into each bowl before topping with bread and cheese. Decadent.

• •

  Vegetarian — use a rich mushroom or vegetable broth and double the Worcestershire (or use a vegan version). Skip the beef.

• •

  Add a slug of dry sherry or madeira at step 5 in place of cognac for a deeper, nuttier flavor.

• •

  Pressure-cooker onions — sauté 10 minutes then pressure cook on high 25 minutes; finishes the caramelization in less time with similar results.

Storage

Refrigerate the soup base (before bread and cheese) up to 5 days; freezes 3 months. Always toast bread and add cheese just before serving — soup with bread doesn't keep, it goes soggy.

Frequently Asked Questions