1. Combine 2 cups boiling water and tea bags in a large bowl; steep 5 minutes. Discard tea bags. Add sugar to tea mixture, stirring until sugar dissolves. Cool completely. Stir in juice and 1 cup ice water; chill 1 hour.
2. Pour tea mixture into the freezer can of an ice-cream freezer; freeze according to manufacturer's instructions. Spoon sorbet into a freezer-safe container. Cover and freeze 1 hour or until firm. Garnish with mint sprigs, if desired.