Duck + Pomegranate Braise

In Gilan province, where this dish originated, they like their fesenjun/fasujan sour. They also prefer it almost black, which they achieve by dropping a horseshoe/na’l-e asb into the pot. (Perhaps the iron helps the oxidation. They remove the horseshoe once the braise is done and keep it handy in the kitchen for the next time.) The walnuts are ground using a mortar and pestle/namak-yar. The classic combination of pomegranate and duck, loved by Iranians, reflects the abu