01 - Line an 8x8-inch baking pan with parchment paper, allowing overhang for easy removal.
02 - In a blender, combine watermelon cubes, lime juice, lime zest, and sugar. Blend until completely smooth.
03 - Taste the mixture and adjust sweetness or lime to preference.
04 - Pour the puree into the prepared pan. Tap gently to level.
05 - Freeze for 4 hours, or until firm.
06 - Lift the frozen mixture with the parchment, and cut into bars with a sharp knife.
07 - Garnish with fresh mint and lime wedges before serving, if desired.