Watermelon has never been my favorite. There, I said it! I have always been ashamed to admit it. I feel like it makes me less of an American. But I sure did change my mind after drinking this refreshing frozen concoction.
Place the watermelon cubes in a single layer on a baking sheet, and freeze until solid, about 2 hours.2.
While the watermelon freezes, bring the sugar and water to a boil in a small saucepan over medium-high. Add the mint sprigs, reduce the heat to low, and simmer 5 minutes. Remove the syrup from the heat, and let cool 30 minutes. Remove and discard the mint sprigs. Chill until cooled, at least 30 minutes.3.
Combine the frozen watermelon, mint syrup, rum and lime juice in a blender; process until smooth, 8-10 seconds. Stir in the club soda. Divide the mixture evenly among 8 glasses. Garnish each with a watermelon wedge, lime wedge and mint sprig, if desired.