01 - Combine cubed watermelon and fresh lime juice in a blender. Blend until completely smooth and uniform in texture.
02 - Pour the blended mixture through a fine-mesh sieve into a clean pitcher to remove any pulp or fibers, ensuring a silky consistency. Skip this step if you prefer a thicker texture.
03 - Distribute the strained watermelon puree evenly among four tall glasses, filling each about one-third full.
04 - Place one generous scoop of vanilla ice cream into the center of each glass, allowing it to rest on top of the watermelon puree.
05 - Slowly pour the chilled lemon-lime soda over the ice cream in each glass, tilting the glass slightly to control the flow and allowing the foam to rise without overflowing.
06 - Top each float with fresh mint leaves and watermelon balls or slices. Serve immediately with straws and long spoons while the ice cream is still firm and the soda is effervescent.