Watermelon and raspberry cooler

oranges 3
raspberries 125g
watermelon 1kg, skin -on weight
mint leaves 12

Slice one of the oranges in half and then cut each half into 3 segments, place on a frost-proof tray or in a plastic container and then in the deep freeze. Leave for a couple of hours.

Put the raspberries in the jug of an electric blender. Remove the skin from the watermelon, discard, then slice the flesh into large chunks picking out the seeds as you go. Add the watermelon to the raspberries together with the juice of the remaining oranges.

Process until smooth, adding chilled mineral water if the consistency seems too thick. Pour into glasses, add a frozen orange slice to each and a mint leaf or two.