Soak the black gram in water for 3-6 hrs or overnight.
Drain the water from black gram dal.
Grind together dal, pepper, green chilli, ginger and salt with very little water just enough to grind.
Beat the batter with hand in order to ferment it for 5-10 min. Mix the chopped onions and cumin seeds with this batter.
Heat the oil for deep frying and maintain the heat in medium low.
For every vada, dip your hand in water and immediately place sufficient batter in your palm and shape it into a doughnut and drop in the heated oil for deep frying.
Keep making the doughnut shaped fritters until you exhaust the batter.
When the vada has light brown color on the outside, it can be removed from the oil.
It goes very well with coconut chutney.