Soak Idli rice, Urad Dal and Sago separately for 4 hours.

Grind Urad Dal first with little water until fluffy.

Now Grind soaked rice and Sago into a smooth batter.

Transfer the batter to a large vessel and mix both batter along with salt using hands and Ferment it for 8 hours.

After 8 hours, steam the idli in a greased idli plate for about 8 to 10 minutes. Make sure you arrange the idli plates in such a way that it shouldn't touch.
Because after it cooks, I will rise a lot. It will touch the above idli plate.