Soak all the dals together for half an hour. Place in a colander to drain. Grind the soaked dals, red chillies, curry leaves, ginger, salt and a little water to a coarse batter.
Transfer the batter to a bowl; add the onion, green chillies, asafoetida and coriander leaves and mix well. Add salt to taste. Heat the oil in a kadai.
Shape the batter into one-and-a-half-inch round balls, press slightly to flatten and deep-fry over medium heat till golden brown and crisp.
Drain on absorbent paper and serve hot with chutney.