In a large mixing bowl., combined all the ingredients. Mixed well. Cover & set aside in warm place for 2 hours for the yeast to activate and batter doubled in size.
Heat oil in frying pan, scoop several tablespoon of the batter into the hot oil. fry on both sides till they are golden brown. Transfer the cooked vadai onto a kitchen towel to absorb excess oil. Good on its own or eaten with fresh green chilies.