Soak raw rice, black gram, fenugreek seeds in water for 2 hours. In a wet grinder or mixer grind them to coarse batter. I.e. to rava consistency.
Now add to the batter black pepper, cumin seeds, curry leaves, asafoetida powder, crushed or powdered dry ginger, salt. Mix well and keep this aside for 10 to 12 hours.
Once the batter is fermented. Place banana leaf in a aluminum bowl and fill batter half. Now steam cook this for 20 to 25 minutes until the idli is cooked then serve. NOTE: idli is done when Insert a clean matchstick (back end) or a skewer. The skewer should come out clean if the idlies are done.
Goes well with onion chutney.
You can also cook the idlies in idli cooker as well.