Wash urad dal and soak for at least 3-4 hours. 1 ½ - 2 hours might also work but I always soak at least 3-4 hours.
Discard water and wash dal again. Put in a strainer or a colander to drain water.
Grind urad dal, green chilies and salt to a almost smooth paste/batter, using about ½ cup water. The batter should be thick, just like medhu vada batter.
Transfer the batter to a wide bowl, add rest of the ingredients except oil. Mix to combine all the ingredients evenly and also to aerate the batter.
Drop a pinch of batter in water to test the consistency of the batter.
If batter floats, the batter is of the right consistency and if it sinks to the bottom of the bowl, the batter is too thick. Add some water.
Heat oil in a wok or a wide pan for deep frying the bonda.
When oil is hot, reduce the flame to medium.
Wet hands and take about gooseberry sized batter and shape into a round ball. Gradually drop into oil.
Depending on the size of the wok, fry 5 - 6 bonda per batch.
Fry bonda, turning them around until golden brown, about 3-5 minutes.
Remove from oil and let drain on paper towels.
Repeat the above steps to fry rest of the bonda. I did it in 4 batches.
Serve hot with coconut chutney.