Add all the ingredients to a non reactive bowl and mix till the sugar has dissolved.
Pour into a clean baking tray and place in the freezer for 1 hour.
Remove after 1 hour and scrape from the edges using a fork to form the crystals. Freeze again.
Repeat this every 30 minutes for the next 2 hours.
The quantities of sugar and lemon juice/verjuice will need to be adjusted according to the flavour profile of the wine. So taste after mixing all the ingredients and adjust levels of lemon juice and sugar.