Grapes, as many as you like
Destem the grapes, removing any bad ones. Wash.
Put all grapes into a large saucepan, mash with a potato masher. Slowly bring up to the boil,, simmer for 10mins stirring and mashing throughout.
Line a colander with muslin/cheesecloth, pour grape juice into the lined colander, allow to cool then place in the fridge overnight to cool and finish staining.
Serve over ice topped with sparkling water