In a large bowl, pour prosecco and vodka over grapes. Let soak in fridge at least 1 hour.
Drain grapes in a colander and pat dry, then transfer to a small baking sheet and pour sugar on top. Shake pan back and forth until grapes are fully coated in sugar.
Serve in a bowl.
Notes
Get more prosecco flavour by lightly piercing each grape to allow the prosecco to mix better.I also recommend putting these grapes in the freezer for a few hours for a true icy treat!