01 - Combine cubed watermelon and lime juice in blender. Process until completely smooth and liquefied.
02 - Pour puree through fine-mesh sieve into pitcher, pressing with spoon to extract juice. Discard pulp for silky texture.
03 - Distribute strained watermelon puree equally among four tall glasses.
04 - Place one generous scoop vanilla ice cream into center of each glass.
05 - Slowly pour chilled lemon-lime soda over ice cream, allowing foam to rise naturally.
06 - Top with fresh mint leaves and watermelon garnish. Serve immediately with straw and long spoon.