Place the grapes, water and sugar in a non-reactive saucepan. Simmer the grapes until they start to fall apart (about 3-5 minutes). Remove from the heat before they gel-this happens quickly!

Strain the grape mixture through a fine mesh strainer to remove the solids. You should have 3 cups of grape juice.

Whisk in the remaining ingredients and chill the mixture at least 4 hours or overnight.

Process the grape juice in an ice cream machine according to manufacturer’s instruction.