Soak 2 cups idli rice and 1/2 cup urad dal separately for 4 to 6 hours
Grind urad dal to a smooth, fluffy batter
Grind rice to a slightly coarse batter
Mix both batters with salt
Ferment the batter for 8 to 12 hours or until it rises
Grease idli moulds with oil
Pour batter into the moulds
Add 2 cups water to the pressure cooker
Place a stand inside the cooker
Keep the idli mould stand on the stand
Close the cooker without the whistle
Steam on medium heat for 10 to 12 minutes
Turn off the heat and let it rest for 2 minutes
Remove the moulds carefully
Let the idlis cool slightly
Unmould and serve hot