French Onion Soup Recipe

Melt the 50 g butter with the 1 tbsp olive oil in a large, heavy-based pan over medium heat. Add the 1 kg sliced onions and cook, lid on, for about 10 minutes, until they've softened.

Sprinkle in the 1 tsp sugar, then remove the lid and continue to cook for another 20 minutes or so, stirring frequently, until the onions are deeply golden and caramelized. They should be very soft when pinched between your fingers; keep a close eye on them towards the end to prevent burning.