Separately soak the rice and urad dal, then grind them into a smooth batter.
Idlis become soft and fluffy when the batter is left to ferment overnight.
To the fermented batter, add salt and toss just enough to combine.
To prevent batter from sticking, grease small stainless steel bowls or cups.
To give the batter room to rise, fill each basin halfway.
Put bowls in a big steamer pot and let them steam for ten to fifteen minutes.
Allow to cool somewhat, carefully remove the mould, and serve warm with sambar or chutney.