4ozs Icing Sugar
Squeeze the oranges and lemon to make just over 1 pint of juice. Stir in the icing sugar and whisk until it dissolves. Transfer to an ice-cream maker and freeze, or pour into a freezer tray. Freeze to a slush, then transfer to a bowl and whisk well, or whiz in a food processor so that the sorbet becomes very light and fine grained. Return to the tray and freeze until firm. Transfer the sorbet to the fridge about 30 minutes or so before eating, to let it soften.