1 cup mint leaves (not packed), plus 4 sprigs, for garnish
1 cup silver rum
3/4 cup simple syrup
1/3 cup freshly squeezed lime juice plus 1 lime, sliced
Combine the ice, mint, rum simple syrup, lime juice and half of the lime slices in the carafe of a blender. Blend until the mint and lime are pureed and the mixture is homogeneous and slightly thick. Pour into chilled serving glasses and garnish each glass with the remaining lime slices and a sprig of mint. Serve immediately.