Forty patient minutes of caramelization, deglazed and crowned with molten Gruyère toast. The dish that proves time is an ingredient.
1 kg
🧅 yellow onions ›
thinly sliced
1.2 l
🍲 beef or rich chicken stock ›
Mise en place
Before you start
Prep checklist
yellow onions — thinly sliced
Melt butter with oil over medium heat and add all the onions with a pinch of salt. They will tower over the pot; they will surrender.
Cook, stirring every few minutes, as the onions collapse, turn gold, then amber, then mahogany — 40–50 minutes. Deglaze the browning film on the pot with a splash of water whenever it darkens.
💡
This is real caramelization. The recipe cannot be rushed, only abandoned — and the smell will keep you honest.
Pour in the wine and scrape the pot clean; let it reduce almost to nothing, 2 minutes.
Add stock, thyme, and bay. Simmer 20 minutes, then season — the stock and cheese both carry salt, so go gently.
Ladle into ovenproof bowls, float the toasts, bury them in Gruyère, and broil until blistered and bubbling, 3–4 minutes.
The soup is a caramelization exam and the reward for passing is dinner. Make a double batch of onions and freeze half — future-you gets this soup in 30 minutes.
Comté or Emmental for Gruyère
Rich vegetable stock + soy splash for beef stock (vegetarian, keeps the umami)
Dry sherry for white wine — deeper, older-school
Afterwards
Keep, reheat & pair
Storage
Soup base keeps 4 days refrigerated and improves overnight. Add fresh toast + cheese when serving.
Freezing
Base freezes 3 months. Never freeze the assembled gratinée.
Reheating
Reheat gently: covered in a 160°C oven for 15 minutes, or in a pan over medium-low with a splash of water or stock. The microwave works at 50% power in short bursts — full blast toughens proteins.
Make ahead
Most braises and sauces improve overnight. Sear-and-serve dishes: do every step up to the final cook, then finish fresh.
Wine pairing
The same dry white you cooked with, or a light Beaujolais.
Beer pairing
Match intensity: lagers for delicate dishes, amber ales for roasted flavors, stouts for the rich and braised.
On the plate
Serve it with
Sides
·
Crusty bread or buttered rice
·
Roasted seasonal vegetables
Garnish
Fresh herbs added off the heat
Where it comes from
A little history
Les Halles market workers ate it at dawn; legend credits Louis XV's hunting lodge. Either way, it is Paris in a bowl.
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