Soak urad dal with enough water keep aside for 4-5 hour.
Grind the dal into a smooth paste, in small quantities by adding minimum water only. grind again till you get a smooth, thick and fluffy paste, the batter has to be as thick as possible. remove the batter in a vessel.
Take the batter vessel and using your hand, beat the batter and combine well for at least 5 minutes, this will create air inside the batter.
Add all the ingredients into the batter . combine well and keep aside.
Oil is heated in a frying pan and ensure enough oil is there for deep frying.
Take your hands a portion of batter, a small tomato (ball) sized and using thumb, make a hole in the center (doughnut shape).
Deep fry over medium flame, till the vada turns brown.
Serve hot with chutney and sambar.