Directions

1. For watermelon simple syrup, put sugar and water in a small saucepan and bring to a boil over medium heat, stirring often, to dissolve sugar. Set pan in a bowl of ice water and stir occasionally until syrup is cool, about 10 minutes.
2. Meanwhile, cut watermelon in half and reserve half for other uses. From the remaining watermelon, cut 1 cup of medium watermelon chunks and set aside. Dice 1 cup watermelon and set aside. Cut the rest of the watermelon into large chunks (about 4 cups). Puree the large chunks in a blender, then pour and rub the watermelon juice through a fine strainer. You’ll have about 1 ½ cups watermelon juice.
3. Pour cool syrup into a blender and add diced watermelon and 2 tablespoons lime juice. Whirl until very smooth, about 2 minutes; strain. You’ll have about 1 ½ cups watermelon simple syrup.
4. To make the mockjito, in a cocktail shaker, muddle the medium chunks of watermelon with mint leaves to release the juice and oils. (If you don’t have a muddler, stir vigorously with a wooden spoon, breaking up watermelon and mint.) Add 2 ounces (¼ cup) watermelon syrup, 2 ounces (¼ cup) watermelon juice, the remaining 2 ounces (¼ cup) lime juice, and a handful of ice cubes. Shake vigorously until cold, then pour into 2 glasses.
5. Top drinks with sparkling water. Add a lime slice, mint sprig, and watermelon wedge to each. Leftover watermelon juice and watermelon simple syrup keep, chilled, up to 1 week; stir before using.