Key lime sorbet
In a small heavy saucepan, dissolve the granulated sugar in 600ml/1pt water, without stirring, over a medium heat. When the sugar has dissolved, boil the syrup for 5–6 minutes. Remove from the heat and leave to cool.
Mix the cooled sugar syrup and lime zest in a bowl. Stir well. Add the lime juice, and stir in the icing sugar. Freeze the mixture overnight in a shallow freezer container, occasionally breaking up any large crystals with a fork if necessary.