- 50g (1¾oz) butter
- Olive oil
- 1.25kg (2lb 8oz) brown onions, peeled and sliced
- 3 cloves garlic, crushed
- 2tsp fresh thyme leaves
- ½tsp plain flour
- 1.5l (48fl oz) good quality beef or chicken stock
- 1 bay leaf
- 1 baguette
- 125g (4oz) Gruyere cheese grated
- Heat the butter and about 2tbsp olive oil in a large heavy saucepan over a low heat. Add the onions, garlic and thyme and give them a good stir. Cover the saucepan with a lid and cook, stirring occasionally, for about 15 minutes.
- Remove the lid, turn up the heat a little, sprinkle with the sugar and cook, stirring frequently, for another 15 minutes, or until the onions are golden.
- Add the flour and cook for 1 minute, then add the stock and bay leaf. Turn the heat down and simmer for about 30 minutes. Season to taste with salt and freshly ground black pepper.
- Heat the oven to 180°C (gas mark 4). Cut 6 thick slices of baguette, placing them on a baking tray and cook in the oven for about 5 minutes, turning once, until crisp. Pour the soup into deep ovenproof bowls and place the slice of bread on top. Sprinkle some Gruyere on top of the bread, placing the bowls on a baking tray and transferring to the oven until the cheese has melted.
The onions have the best flavour when cooked slowly over a low temperature. When cooking, stir regularly and keep an eye on them to make sure they don't burn.