First, make the grapes ice cubes. Place a few sliced grapes in ice cube molds and fill with grape juice. Freeze overnight or until ice cubes are solid.

In a large pitcher, combine lime juice and mint leaves and crush with a wooden spoon to muddle. Then add remaining grapes, grape juice (save a little for rim) and sparkling water.

To serve, mix a little grape juice with granulated sugar. Rim cups with lime juice and then the grape sugar mixture. Place ice cubes in glasses, and then pour spritzer into glasses and garnish with limes and mint.