1 (2-pound) piece seedless watermelon, rind removed and cut into chunks
3/4 cup club soda or ginger ale, chilled
Juice from 3 limes
1/2 cup grenadine
Place watermelon and remaining ingredients in a bowl; puree with immersion blender until smooth. Pour into an ice-cream maker. and freeze according to the manufacturer's instructions for about 30 minutes. Pour into a bowl, seal lid, and place in freezer for 15 more minutes.