Pour boiling water over tea bags in a large saucepan; steep 5 minutes. Remove and discard tea bags. Add sugar to pan; cook over medium heat 5 minutes or until sugar dissolves. Cool completely.
Combine tea mixture, grapefruit juice, orange rind, and orange juice in 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.