Onion soup

Ingrediënten

• Groundnut or grapeseed oil
• 1kg peeled and finely sliced onion (approx. 5 large onions)
• 2 star anise
• 30g unsalted butter
• 150g dry white wine
• 1kg beef stock (p.40)
• 2 tbsp dry madeira, plus extra for finishing
• Salt and black pepper
• Sherry vinegar
• To finish and serve
• 2 slices of sourdough bread, halved
• Unsalted butter, for frying
• Dijon mustard
• 100g grated gruyère cheese
• 1 tbsp chopped chives
• 2 spring onions, finely sliced