This sweet and tart cocktail is packed with light, natural flavors perfect for spring evenings. In a cocktail shaker, muddle four mint sprigs, 1 ounce of simple syrup, 1 ounce of fresh-squeezed lemon juice and 2.5 ounces of grapefruit juice. Add 1.5 ounces of Papagayo Platinum Rum and shake with ice. Strain into a Collins glass over ice and top with club soda and a splash of Angostura bitters. Stir. Garnish with grapefruit and mint.