Prepare your freezing pans by making sure the pan size you choose has sides that will keep the grapes from rolling off and that it will fit in your freezer.
Remove the grapes from their stems and wash them under cold, running water. (This is easier to do if you use a colander or a large strainer.)
Pat the grapes dry with paper towels.
Fill a large, shallow bowl with 1 cup of Prosecco or champagne and 1 cup of tequila or vodka. Mix them together with a whisk.
If you have too many grapes in your bowl and the liquor mixture doesn't cover them, simply add additional amounts of each liquid to completely cover the grapes.
Leave the liquor mixture and the grapes on the kitchen counter at room temperature.
Let the grapes marinate in the liquor mixture for 1 hour. (Longer is okay but don't let the liquor evaporate.)
Once the grapes have marinated in the liquor mixture for at least 1 hour, fill a shallow bowl with white (granulated) sugar and roll the grapes in the bowl, one by one.
As you roll the grapes in the white sugar, place them on the pan you've chosen with a small space separating them from touching each other.
Once the pan is full of sugared grapes, place it in your freezer in a nice flat space and let the grapes freeze overnight.
In the morning, get out a freezer bag, pluck the frozen grapes off the freezing sheet, and place them in the bag. Seal the bag, place it back in the freezer, and proceed marinating and freezing more grapes if you've chosen to make more than 2 bunches.
Serve these grapes frozen. They're very refreshing on a hot, summer day and a great addition to a barbecue or a pool party.
