Spread watermelon
cubes
on a tray lined with plastic wrap or parchment (for easiest removal) and chill in freezer until frozen. Add
sugar
to
lime juice
and stir to combine; sugar should dissolve in a minute or two. Place frozen watermelon, sweetened lime juice, and
rum
in
blender
and blend until thick but smooth. Add
mint
and pulse a few more times, so that is chopped but not pureed. Pour into two glasses. Top with a splash
of seltzer
if you wish, finish with lime wedges and extra mint. Repeat all summer.
cubes: 1 pound (watermelon in 1-inch, a scant 4 cups, from about 2 pounds with rind on),
sugar: 1-2 tablespoons (granulated),
lime juice: 1/2 cup (fresh, from 3 to 4 limes, plus wedges for serving),
rum: 3-4 ounces (white, 6 to 8 tablespoons),
mint (leaves from 1 to 2 sprigs of fresh, plus extra for garnish),
of seltzer (two splashes)
