Use 600 ml/ 1 pt red wine vinegar to each 450 g/ 1 lb raspberries. Blitz the fruit to a purée in a food processor and transfer to a bowl. Pour the appropriate amount of vinegar over, cling-wrap the top and leave to macerate at room temperature for a week.

Put into a saucepan and bring to the boil. Lower the heat and simmer for 15 minutes. Pass through a muslin-lined sieve. Bottle and keep in a cupboard (as exposure to light results in a more rapid loss of fruit flavour). It will not keep for ever and is best used within six months.

Use it to finish sautéed meat dishes.