Remove the grapes from the stalks, discarding any brown grapes, then wash and dry thoroughly before freezing. Preparation of the fruit is important for really good, clean results with the best flavour.
Grapes are best frozen in a flat layer. This allows each one to freeze really thoroughly, but also aids them not to stick together during freezing, which would make it a lot harder to separate and blend once frozen!
Make sure to use a really powerful blender for the smoothest results. If your food processor isn't powerful enough, you could try using a smoothie maker instead before transferring the whizzed up sorbet into a container and freezing again until firm.
Add in a few torn mint leaves if you wanted a slightly mintier flavour to the sorbet. This requires a really powerful blender to work or you will have bits of unblended mint throughout the sorbet.
When scooping, dip the ice cream scoop in water, then shake it off before scooping for perfect balls of sorbet. Re-dip in between scoops for clean results.