Persian Rice With Barberries Zereshk Polow

Name: Persian Rice With Barberries (Zereshk Polow)
Ingredients: 1 cup rice (the kind you have to soak a long time from a Iranian shop); water; 1⁄2 cup dried barberries (found in Iranian shops); 2 1⁄2 tablespoons white sugar; 2 tablespoons saffron water (Persian Saffron Water); 5 tablespoons butter, divided; 1⁄8 teaspoon advieh persian mixed spice (Advieh - Persian Spice Mix); sea salt, to taste