Soak urad dal for one hour.Remove the water and grind it in mixer or wet grinder to make smooth paste by adding very little water. Add little salt also to make it paste.

Take curd in a bowl and whisk it nicely and add salt.Heat oil and add mustard seeds, jeera, red chilli, hing and curry leaves and splutter it and pour it in the whisked curd.

Take the batter in bowl and mix well for 2 mins.

Heat oil in a deep frying pan. Take the batter with wet hand and make small hole in between and drop it carefully in hot oil.Some people use spoon to drop the batter in the oil. Making hole in between the vada allows it cook nicely inside also.Fry it till golden on both sides.

Take some hot water in a bowl.Place the vada in hot water and press it nicely to drain water and put in the curd.Continue this process with remaining batter.

Allow vadas to soak for 2 hour and then serve it by putting jeera powder and red chilli powder and coriander leaves.