In a cocktail shaker, add mango, mint leaves, lime juice and simple syrup. Muddle (mash) until mango is mostly liquid.
Fill with ice, add rum and shake
Double strain using a cocktail shaker top and a small strainer. Pour into chilled martini glass and garnish with a sprig of mint.
Notes
*Simple syrup - Boil equal parts of water and sugar until sugar has melted. Cool before use. This is a common cocktail ingredient - make a large batch and keep in the refrigerator for your next cocktail celebration.