Mix all the ingredients (except oil for deep frying) to form a dough. Let stand for 20 minutes. Apply a little bit of oil to your palms and make small balls of equal size and press them in your palms so as to form a small patty. Dab the center of the patty with your index finger. In the meantime, heat oil for deep frying. Once the oil is hot deep fry the vadas until the outer layer is golden brown. Make sure that the temperature is on high when you put the vadas into the deep fryer, once they rise to the surface bring back the heat to the lowest level and fry until golden brown.
Makes about 25-30 vadas