01 -  Place watermelon chunks, mint leaves, lime juice, and sugar in a blender or food processor. Blend until completely smooth. Taste and adjust sweetness if desired. 
 02 -  Pour the mixture through a fine mesh sieve into a shallow, freezer-safe dish to remove pulp (optional for extra-smooth texture). 
 03 -  Freeze the mixture for 45–60 minutes, then use a fork to scrape and break up any ice crystals forming at the edges. 
 04 -  Return to the freezer. Every 30 minutes, scrape the mixture with a fork, repeating 3–4 times, until the granita is fully frozen and fluffy with fine crystals (about 4 hours total). 
 05 -  Fluff with a fork and spoon into chilled glasses. Garnish with fresh mint leaves and serve immediately.