sour grapes
Green, unripe grapes, very sour and barely sweet; used in Persian cooking whole, as juice, or dried and ground.
Ghooreh are grapes picked before they develop sugar, while they are still small, hard and green. They taste sharply sour, fresh and slightly astringent, similar to lemon but rounder, with a green, fruity note. Simmered whole they soften but keep their acidity and burst in the mouth, giving stews both sourness and texture. There is also the pressed juice (abghooreh, the same as verjuice) and the dried powder (gard-e ghooreh). They are sold frozen or in brine at Persian and Arab grocers, the juice also at Turkish supermarkets and by mail order; anyone with a grapevine can pick them in early summer and freeze them.
Substitute:
For the acidity, use verjuice or abghooreh, or failing that lemon juice, which tastes sharper and less fruity; none of these replaces the whole berries that burst in the mouth, so the dish loses that texture.