Combine the melon, cucumber, sugar, lemon juice and 1 cup water in a blender and puree until smooth. Strain through a fine-mesh sieve into a pitcher, using a ladle to push the mixture through.
Add the vodka and liqueur to the pitcher and stir to combine. Refrigerate until cold, at least 30 minutes or up to 4 hours. Divide among ice-filled glasses; garnish with cucumber spears.
Photograph by Ryan Liebe
Courtesy of Food Network Magazine