How to Make It
In a small saucepan, combine the water with the sugar and cook over moderate heat, stirring, until the sugar dissolves. Let cool completely.
In a blender or food processor, puree the melon with the lemon juice, mint and sugar syrup. Fill 4 large glasses with ice and pour in the melon puree. Top with seltzer, garnish with mint and lemon slices and serve.