Verjuice

Verjuice (/ˈvɜrˌdʒuːs/VUR-jooss; from Middle French vertjus "green juice") is a highly acidic juice made by pressing unripe grapes, crab-apples or other sour fruit. Sometimes lemon or sorrel juice, herbs or spices are added to change the flavour. In the Middle Ages, it was widely used all over Western Europe as an ingredient in sauces, as a condiment, or to deglaze preparations. It is still used to some extent in the American South.