Carefully examine the raspberries and pick over, rinsing very gently in cold running water using a colander. 

Place the raspberries into a large suitable container and pour in the vinegar, cover and leave to stand for two weeks in a cool place to macerate the fruit.

Strain through a jelly bag or muslin and measure the liquid. Put the sugar and juice into a saucepan. Set the pan over a low heat, stir until the sugar dissolves and then continue stirring until boiling. Pour immediately into hot sterilised bottles or suitable hot jars and seal. 

Leave to mature for a month.