A great substitute for lemon or lime that is made from unripe grapes.
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.
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.
Pour the juice into a mason jar and keep it in the fridge.
Find it online: https://www.giverecipe.com/homemade-fresh-verjuice/