Rice—called polo in Farsi—is a staple side dish in Persian cuisine. It’s often prepared by steaming with oil or butter to create a crispy layer of rice on the bottom of the pot called tahdig (pronounced tah-deeg). Tah means bottom and dig means pot in Farsi—it’s literally what happens at the bottom of the pot.
This caramelized, crispy crust is often the most prized part of Iranian rice dishes such as katteh (rice simply steamed with water, oil, butter, and sometimes saffron), baghali polo (rice with dill and fava beans), and sabzi polo (herbed rice). In all of these dishes and more, rice is blanched to an al dente texture and then transferred to an oiled pan to finish cooking by steaming, during which time the oil at the bottom of the pan helps form the golden crispy tahdig.