1. Blend all the ingredients except the mint sprigs or raspberry leaves until the ice is crushed.
2. Serve immediately in tall glasses, garnished, if you like, with mint or raspberry leaves.
Variations Instead of raspberries, try 2 large peaches, peeled and sliced; 4 slices pineapple, fresh or canned; 1 large ripe mango; 150 g (6 oz) either strawberries, blackberries, blueberries, blackcurrants or red-currants.