Puree watermelon along with lime juice and then strain to remove the seeds. Pour the strained puree into a 9*13 inch baking pan or any freezer safe container.

In a separate pan, combine sugar with water and lime zest. Stir on a low heat until the sugar has dissolved. Turn off the flame and allow it to cool.

Pour the cooled lime syrup into the watermelon puree, and stir to mix it well.

Freeze for 30 minutes (uncovered). Once it starts to set along the edges, scrape using a fork to break the ice into tiny crystals, and freeze again. Repeat this process at 30-minute intervals for the next 3-5 hrs or until it has formed a shaved ice consistency.

Keep it frozen until ready to serve. Serve by scraping into the serving glass and top with mint leaves.