Makes one cocktail.
Place 1 mint leaf and simple syrup into glass. Muddle mint leaf. Add ice and whisky. Top with lime juice and a splash of seltzer water. Stir and garnish with a mint leaf.
*Mint syrup: 1 cup water, 1 cup sugar, ¼ cup mint leaves; Combine ingredients over low heat, stirring constantly. Remove from heat and cool at least 30 minutes before straining out mint leaves. Yields 1 cup