- 100 g butter
- 2 kg brown onions, peeled and sliced thinly
- 2 garlic cloves, peeled and chopped
- 1/4 bunch thyme, leaves finely chopped
- 2 sprigs rosemary, leaves finely chopped
- 1 tablespoon flour
- 3 liters good quality vegetable stock, heated
- For the croutons:
- 1 baguette
- 1 head garlic, cut in half horizontally
- 60 g butter, melted
- 100 g gruyère cheese, grated
- Sea salt and white pepper, to season
Place a large heavy-based stockpot over low heat. Add the butter, then the sliced onions and sauté for about 20 minutes until soft and translucent.
Add the chopped garlic, thyme and rosemary and continue cooking until the onions begin to become golden brown and very soft. This will take up to 30 minutes. Stir the onions continuously. Sprinkle over the flour and cook, while stirring, for a further 5 minutes.
Add the hot vegetable stock to the onion/flour mixture. Continue stirring to avoid the flour from becoming lumpy. Cover and cook for 30 minutes on low heat. The onions should be tender, almost melting into the liquid. Season with salt and white pepper.
To make croutons, rub the garlic over the baguette, slice, then brush with melted butter. Sprinkle each slice of bread with grated gruyère cheese, place on a baking tray and put under a hot grill until the cheese is melted and golden.
Ladle the soup into eight bowls and float a crouton on top. This can also be served from one large soup tureen.