6 cups ripe seedless watermelon, cubed
3 Tbsp lime juice, plus lime slices for serving
3½ cups cold water
½ cup cane sugar
2 Tbsp fresh mint, plus sprigs for garnish
Pinch of sea salt
3 cups ice cubes
Mix ½ cup cold water with ½ cup cane sugar. Bring to boil over medium-low heat and simmer, without stirring, until sugar is dissolved (3 minutes). Remove from heat. Press mint leaves between palms of hands to release oils, and add to simple syrup. Steep 15 minutes. Remove mint leaves and set aside.
Blend watermelon, lime juice and 3 cups cold water at high speed until smooth. Stir in a pinch of salt and 2 tablespoons mint-infused simple syrup. Taste and add additional syrup if desired.
Pour through a fine mesh strainer and serve over ice. Garnish with lime slices and mint sprigs.