Wash and soak dal in about 3 cups of water for about 4-6 hours.
Drain the water and grind dal to smooth paste using very little water just enough to grind. Blend for another 2 minutes to whip dal to make fluffy. Take dal batter out in a wide bowl.
Add all the ingredients to the dal batter, cilantro, green chili, ginger, curry leaves, asafetida and salt, beat the batter for 2-3 minutes this will make the batter light and fluffy. To make sure batter is ready put one drop of batter in a bowl of water, batter should float.
Keeping the right consistency of batter is very important; add water as needed batter should not be soft but not runny. When you put the batter on your palm batter should hold its shape. Make the Vadas batter when you are ready to fry them, as the batter sit will get soft if you are not ready to fry keep batter refrigerated.
Heat the oil in a frying pan over medium high heat.
To check if the oil is ready, put one drop of batter in oil. The batter should sizzle and come up but not change color right away. If oil is very hot Vadas will not cook through and will not be crispy.
Wet the palms and take golf size batter and place over your palm, flatten to round shape and make hole in the center looking like donut now with other hand wet fingers slowly slide Vada into the hot oil.
Fry the Vadas from both sides to golden brown. Take them out over paper towel to drain access oil.