1: Heat the olive oil in a saucepan over a medium heat.

2: Add the peppers, shallots and chilli and fry, stirring, for 3–5 minutes until softened. Add the saffron, reduce the heat to low and leave to slowly cook for 20–25 minutes until the peppers and shallots are very tender.

3: Stir in the wine, sugar and white wine vinegar, increase the heat to medium and leave to simmer, uncovered, until almost all the liquid has evaporated.

4: Transfer the sauce to a blender and purée. Add the butter, which will give the sauce a shine, and blend again.

5: Season, then pass the sauce through a sieve. Leave to one side to cool until needed.