Rinse 2 cups idli rice and 1 cup urad dal separately
Soak the rice and dal separately in water for 4 to 6 hours
Drain the water from both
Grind the urad dal to a smooth, fluffy batter with little water
Grind the rice to a slightly coarse batter with little water
Mix both batters together in a large bowl
Add salt to taste
Cover and let the batter ferment for 8 to 12 hours or until it rises
Grease idli molds with a little oil
Pour the batter into the molds
Place the idli stand in a steamer
Steam for 10 to 12 minutes
Turn off the heat and let it rest for 2 minutes
Remove the idlis from the molds
Serve hot with chutney and sambar