Warm idlis slightly over boiling water in a colander. Pass idli through large holed sieve, till it looks like bread crumbs. Add salt,sugar, keep aside. Heat oil in small pan, add seeds, allow to splutter. Add curry leaves, asafoetida, chilli, ginger. Pour over idli crumbs, add to sieved idli. Toss gently with hands, till well mixed.