Soaked urad dal and rice with water separately for 3 to 4 hours, wash and drain the water, mix well and blend for smooth paste

Cover it with a lid and keep aside to ferment in a warm place for 10 to 12 hours or overnight

Now combine the cumin seeds and black peppercorn in a mortal pestle, cruse to a coarse mixture and keep aside

Heat pan add oil, chana dal and saute in a medium flame for 1 minutes

Now add mustard seeds, hing, urad dal, cumin seeds and black peppercorn mixture, chopped green chillies, and saute few more time

Steam in an idly steamer for 10 minutes or till they are cooked

Reapete with the remaining batter to make more idlies

Allow the idlies to cool slightly and then demold