firstly, in a large bowl soak 1 cup urad dal for 2 hours.
also, soak 2 cup idli rice for hours.
after, 1 hour of soaking of urad dal, drain off the water and transfer to the grinder.
grind for 45 minutes adding water as required. use urad dal soaked water for grinding, as it helps in fermentation.
scrape the sides and grind until the batter turns soft and fluffy.
transfer the batter to a large vessel and keep it aside.
in the same grinder add soaked rice and grind.
grind to a coarse paste adding water as required.
transfer the rice batter to the same vessel.
mix well making sure everything is well combined. mixing the batter with hand helps to aid fermentation.
cover and ferment in a warm place for 8 hours.
the batter is well fermented when it has doubled in volume.
mix the batter gently, without disturbing the air pockets.
add 2 tsp salt and mix gently.
grease the idli plate with oil and pour the batter.
steam the idli for 10 minutes or until the toothpick inserted comes out clean.
finally, enjoy soft idli with chutney and sambar.