Place the sugar and mint leaves in a food processor.
Process until finely minced.
Add the cubed watermelon, lime juice and pinch of salt.
Puree until smooth (total amount of liquid is about 4 cups, as per markings on the food processor).
Pour watermelon puree mixture in a shallow stainless steel pan and place it in the freezer.
Stir to break up the ice every 60 minutes or so (with a fork) for 3-4 hours. The consistency should be granular but still slushy.
At this point, cover and allow to freeze undisturbed for at least 2 hours.
When ready to serve, grate the top (with a fork) and place in serving dish.
Decorate with mint leaves and a lime wedge (if desired).
Feel free to adjust the amount of sugar that you add according to personal preference.Please keep in mind that the nutritional information provided below is just a rough estimate and variations can occur depending on the specific ingredients used.