A simple overnight infusion of fresh shiso leaves in gin can speed up preparation of this cocktail and make it easier to fix en masse, but the infusion isn’t strictly necessary. If mixing on the fly, simply add three torn shiso leaves to the mixing glass along with the other ingredients (increase the gin to 2 oz. since you won’t have the infusion on hand) and let everything sit for a few moments before adding the ice and stirring. To serve, rub a torn shiso leaf around the rim of the cocktail glass to boost the aromatics.