Ginger Sorbet

Combine sugar, ginger, lemon zest and water in a heavy-bottomed saucepan. Bring to a boil, stirring often. Boil, uncovered, over medium heat for 10 minutes. Cool. Stir in lemon juice. Freeze the mixture in an ice-cream maker, following manufacturer's directions. Break into chunks and whirl in a food processor until smooth. Transfer to a chilled airtight container and return to the freezer for 30 minutes to 1 hour, or until firm.