Combine first 3 ingredients in a medium bowl; stir well. Cover and steep 5 minutes. Strain tea mixture through a fine sieve into a bowl; discard tea leaves. Stir lemon juice into tea; cover and chill.
Pour tea into the freezer can of an ice-cream freezer, and freeze according to manufacturer's instructions. Spoon sorbet into a freezer-safe container; cover and freeze sorbet 3 hours or overnight.
