Tandoor, Ranjit Rai, p.~48 : "A certain amount of curing is necessary before the tandoor is fired for the first time. A good new tandoor should be smooth from the inside. Green leaves, usually spinach, are used to coat the inside walls. After a day, a mixture of buttermilk or khatti lassi, oil and salt is rubbed all over the inner walls and left overnight. This curing prevents the rotis and other breads from sticking to the walls of the tandoor when being cooked".