Step 1

Rinse the unripe grapes very well.

Step 2

Put them in a large bowl and mash them with the bottom of a jar. You don't need to remove them from the stems.

Step 3

Transfer the resulting juice into a fine mesh sieve and squeeze in your hands. Make sure to use gloves when doing this. Alternatively, you can strain it with a coffee filter or cheesecloth.

Step 4

Pour the juice into a mason jar and keep it in the fridge.