¾ cup simple syrup (equal parts sugar and water, boiled until the sugar dissolves)
¼ teaspoon kosher salt
2 teaspoons fresh lemon juice
¼ cup, plus 2 tablespoons, water
Directions
In a blender, purée all of the ingredients until smooth. Strain the watermelon mixture into a Pyrex or metal baking dish, and freeze.
When the edges begin to set, after about 30 minutes, use a fork to break the granita apart. Continue to freeze, scraping every 30 minutes, until the mixture is completely frozen and fluffy, 3 to 4 hours.