Serves 4
30g butter
6 tsp olive oil
500g onions, thinly sliced
pinch caster sugar
1.2 litres vegetable stock
1 bay leaf
salt and pepper
4 thick slices French bread
1tsp Dijon mustard
90g grated cheese
Heat the butter and oil together in a pan. Add the onions and sugar. Cook over a medium heat until the onions are a deep golden brown.
Add the stock and bay leaf. Slowly bring to the boil. Cover and simmer for 25 minutes. Remove the bay leaf and season.
Toast bread on each side, then spread with mustard. Pile cheese onto each slice and place under a hot grill until melted and bubbling.
Float bread on soup or serve at side.
