Simmer cranberry juice, sugar and rind, uncovered, in a saucepan (NOT aluminum) 10 minutes, stirring now and then. Off heat, mix in lemon juice; cool, pour into a bottle, cover and refrigerate. Serve as is on the rocks in punch cups or small glasses. OR, half fill a tall glass with shrub, add ice, and fill with club soda. OR, pour into punch cups and top each serving with a scoop of tart sherbet.