Place the cubed watermelon on a baking sheet lined with parchment paper. Make sure the watermelon pieces are spread out in a single layer. Place the baking sheet in the freezer and freeze the watermelon cubes until they are firm, about 2-3 hours.

Once the watermelon cubes are frozen, transfer them to a blender or food processor. Add the granulated sugar, fresh lime juice, and salt to the blender.

Blend the mixture on high speed until it is smooth and creamy, scraping down the sides of the blender as needed. The sorbet mixture should be thick and well combined.

Transfer the sorbet mixture to a shallow dish or container and cover it with plastic wrap. Place the sorbet in the freezer and freeze it until it is firm, about 4-6 hours or overnight.

When ready to serve, remove the sorbet from the freezer and let it sit at room temperature for a few minutes to soften slightly. Use an ice cream scoop to scoop the sorbet into bowls or serving dishes.

Garnish the watermelon sorbet with fresh mint leaves, if desired, for a pop of color and flavor.

Serve the watermelon sorbet immediately and enjoy its refreshing taste!