This recipe was created by Helen Rosner in The New Yorker:
2 oz. bourbon or rye 1 oz. Campari 1 oz. sweet vermouth, such as Carpano Antica A strip of lemon or orange zest, for garnish
Fill a mixing glass with ice. Pour ingredients over ice and stir together. Strain into a martini glass or coupe, or into a rocks glass with ice. Twist the citrus zest over the drink, then drop it in.