Add all ingredients to a cocktail shaker; fill with ice and shake well. Strain into a chilled cocktail glass. Traditionally garnished with a maraschino cherry.
If you're like me and not a fan of the common variety maraschino cherries, substitute Amarena or Luxardo cherries or fresh fruit like the Thomcord Seedless Concord Grapes (pictured) which give a lovely burst of sweet in your mouth, perfectly balancing the tartness of the cocktail.