Grind the dal to a fine paste. Be careful not to make it too watery.
Again, grind coarsely both the rice together and mix the dal and rice pastes.
Add water to adjust consistency that is not too flowy nor too thick. Add salt and mix well.
Cover and keep it to ferment overnight. Next morning, give the batter a nice whisk.
Put the hing, green coriander leaves, and turmeric powder.
Prepare the tempering. On full flame, heat the oil in a thick bottom pan.
Heat water in the Idli steamer and lightly grease each idli mold.
Steam for 12 to 15 minutes on full flame.
Remove when done and let idli cool for 5 minutes and then de-mold.