Shake; double-strain; up; garnish with lemon slice and optional star anise.
Syrup recipe from Ryan Cheityawardana: Bring one part water to rolling boil. Stir in two parts sugar until mixed. Add a bay leaf and swath of grapefruit peel with rind removed, and keep stirring until dissolved, ~3 minutes. Let cool and strain.
Made for the MasterClass Holiday Cocktail Contest.