French Onion Soup

How to make it

1. Peel the onions, halve them through the root, and slice them crosswise into thin half-moons. Keep the slices evenly thick so the whole pot caramelizes at the same rate. ⏱ 15 min
   Chef's tip Slicing crosswise into half-moons rather than lengthwise gives shorter fibres that break down into a jammy mass. Uneven slices leave thin shreds scorched while thick ones are still crunchy.
2. Melt the butter in a heavy-bottomed pot over medium-low heat and toss in the onions with 1 tsp salt. Cover with a lid and let them collapse for 15 minutes, until they are glossy and soft and have released their water. ⏱ 15 min · passive
   Chef's tip The lid traps steam so the onions sweat in their own juice — you want them translucent and swimming slightly, not colouring yet. Any browning at this stage means the heat is too high.
3. Remove the lid and turn the heat up to medium. Continue cooking the onions for 45 minutes, stirring the bottom with a wooden spoon every couple of minutes. They are done when they have collapsed into a deep golden-brown, jam-like mass, and the bottom of the pot is brown without being black. ⏱ 45 min
   Chef's tip Colour can only develop once the water has boiled off, which is why this takes 45 minutes and not 15. Scrape the brown film off the bottom as it forms; if it darkens toward black or smells sharp, add a splash of water immediately.
4. Sprinkle the flour over the onions and stir for 2 minutes, until the flour has disappeared into the mixture and no dry spots remain. The flour lightly thickens the soup so it doesn't separate into clear liquid with a layer of onions at the bottom.
5. Pour in the white wine and scrape the brown bits loose from the bottom with the wooden spoon, so all the fond flavor makes it into the soup. Let the wine reduce for 3 minutes, until the sharp alcohol smell is gone and only a sweet, tangy aroma remains.
6. Add the beef stock, thyme sprigs and bay leaf, and bring the soup to a boil. Reduce the heat and let it simmer partially covered for 30 minutes, until it's dark and tastes rounded and sweet with onion. ⏱ 30 min · passive
7. Fish out the thyme sprigs and bay leaf, and season the soup with salt and freshly ground pepper. Add it in small increments, since both the stock and the cheese on top add salt.
8. Turn on the oven's broiler and toast the baguette slices on a baking sheet for 5 minutes, until they are dry and light golden all the way through. They need to dry out completely, otherwise they will fall apart in the soup.
9. Divide the hot soup among four ovenproof soup bowls and place two of the toasted bread slices on top of the soup in each bowl. Cover the bread completely with the grated gruyère, all the way to the edge of the bowl, so the cheese melts fast to the bowl and holds the bread up above the soup.
10. Place the bowls under the broiler for 5-7 minutes, until the cheese has melted, is bubbling, and has developed dark spots. Stay by the oven, since the crust goes from golden to burnt in under a minute.
    Chef's tip Position the bowls about 10-15 cm below the element — closer and the cheese blisters before it has melted underneath. The dark blistered spots are flavour, so let a few form before pulling them out.
11. Place each bowl on a plate and serve immediately, while the cheese is still bubbling — the bowls are scorching hot. Each diner breaks through the cheese crust themselves with their spoon and pulls the bread down into the soup before the first mouthful.