This recipe is popular all over India. Different communities have their own variations to this recipe. For example, some add sugar to the curds, whilst others temper it with mustard and curry leaves. The Marwaris use moong dal instead of urad dal to make the vadas. Dahi vadas can be eaten as a snack or as part of the meal. The vadas can be made a day in advance and refrigerated. You have only to soak them in hot water and drain just before serving.