You will need about six oranges to make 500 ml (17 fl oz/2 cups) of juice. If blood oranges are not in season, substitute other oranges.
115 g (4 oz/½ cup) caster (superfine) sugar
500 ml (17 fl oz/2 cups) blood orange juice
150 ml (5 fl oz) Champagne
2 tablespoons Campari
1. Put the sugar and 250 ml (9 fl oz/1 cup) of water in a heavybased saucepan. Stir constantly over medium—low heat until the sugar has dissolved, then stop stirring. Bring to the boil, then reduce the heat and simmer for 5 minutes. Cool.
2. Put the sugar syrup, blood orange juice, Champagne and Campari in a blender or processor fitted with the plastic blade. Whizz for 15–20 seconds, or until thoroughly combined. Pour into ice cube trays and freeze for 2 hours, or until firm.
3. Turn the frozen mixture out of the trays and return to the blender or processor. Whizz in 5 second bursts until the mixture forms a coarse, icy purée. Transfer to a plastic container and return to the freezer for 1 hour.
4. Remove the sorbet from the freezer and break it up with a fork. Work quickly, as it will melt quickly. Spoon the sorbet into bowls or glasses and serve immediately.