Barefoot Contessa (en-US)

12 large mint leaves plus 4 large sprigs
1 lime, cut into 8 wedges
½ cup freshly squeezed lime juice (4 limes)
½ cup simple syrup (see note)
1 cup dark rum, such as Mount Gay
1 cup ice, plus extra for serving
1 ½ cups sparkling water, such as San Pellegrino, chilled
1/8 teaspoon kosher salt

Put the mint leaves and 2 of the lime wedges in a large cocktail shaker and muddle them with a muddler or a long-handled wooden spoon. Add the lime juice, simple syrup, rum, and ice and stir 40 times with a long-handled swiveling cocktail spoon or the wooden spoon. Add the sparkling water and salt and stir well.

For each drink, fill a low cocktail glass half full with ice, add a mint sprig and a wedge of lime, and pour over the cocktail mixture. Stir and serve ice cold.

Dark Rum Southsides