Paris's late-night classic — deeply caramelized onions simmered in beef broth, topped with a raft of toasted baguette and bubbling Gruyère.
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.
Serves 4
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Don't shortcut the onion caramelization — sub-30-minute 'caramelized onions' from recipe blogs are not the same dish. Real soupe à l'oignon needs at least 60 minutes of patient stirring.
Beef broth quality is everything. Use homemade or a high-quality bone broth (Aneto, Bonafide). Stock cubes will produce a thin, salty, flat soup — don't bother.
Comté is more authentic than Gruyère for French onion soup, but supermarket Gruyère works fine. Avoid 'Swiss cheese' from the deli — it doesn't melt the same way.
Day-old baguette holds up better than fresh — fresh bread dissolves into the soup. If using fresh, toast it a little darker.
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.
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.
Soupe à l'oignon was a French peasant dish for centuries, made from cheap onions and stale bread. It was elevated to a Parisian icon at the central wholesale market Les Halles in the 19th century, where porters and butchers ate it after night shifts. The gratinée version with cheese is documented in Auguste Escoffier's 'Le Guide Culinaire' (1903).
The heat is too high. Drop to medium-low after the first 15 minutes. Caramelization is a slow Maillard reaction, not a sear — patience is the key ingredient.
Yes — use a rich, dark mushroom-and-vegetable broth (or 'beef-style' vegan broth from a brand like Better Than Bouillon). The depth won't quite match beef but the soup remains excellent.
Traditional French onion soup is served in 'lion's head' ceramic bowls (about 350 ml) with handles — they tolerate the broiler. Any oven-safe ceramic ramekin works. Avoid thin glass bowls; they crack.
Yes — replace the wine and cognac with a 1:1 mix of apple cider vinegar and water at step 5, plus an extra splash of Worcestershire for depth. The character changes slightly but the soup is still good.
Per serving (480g) · 4 servings total
Ask our AI cooking assistant anything about this recipe — substitutions, techniques, scaling.
Chat with AI Chef →Join the conversation
Sign in to leave a comment and save your favourite recipes