What is Zereshk (Barberry)?

Zereshk are the dried berries of Berberis vulgaris, a thorny shrub cultivated primarily in South Khorasan province in eastern Iran, which produces the overwhelming majority of the world's supply. The berries are harvested and dried until they're shriveled, deep red, and intensely sour — a sourness that is almost crystalline, more concentrated than lemon, with a slight floral note underneath. They're small enough that you can fit ten on a teaspoon, and their size is deceptive: a tablespoon added to a rice dish transforms the whole flavor profile.

In Persian cooking, zereshk are most famous for zereshk polo — fried briefly in butter with a pinch of sugar to soften the sharpness, then folded into saffron rice. But they appear in khoresh (stew) fillings, meatballs, stuffed chicken, and even Persian desserts where a hit of tartness is wanted. Outside of Iranian cooking, barberries appear in some Central Asian pilafs and were historically used in European and North American preserves before cheaper souring agents made them commercially inconvenient. The zereshk available in Iranian grocery stores in the diaspora is usually South Khorasan origin, dried and packaged, and its quality varies enough that finding a reliable source is a genuine kitchen concern.