firstly, soak the urad dal in enough water for 4-5 hours.
furthermore, drain the water from the urad dal and keep it aside.
take the urad dal in the wet grinder / mixer. add some of the urad dal strained water and grind.
however, if the batter appears too thick, add some water. grind to a smooth batter.
after that pour in a non reactive deep pan or pot.
furthermore, rinse the idli rava till the water runs clear of the starch.
drain the water well from idli rava by squeezing excess water from idli rava.
mix the squeezed idli rava to the batter well.
make sure there are enough space for batter to raise when fermented.
cover and ferment in warm place for atleast 6 - 8 hours.
you can see the batter has raised slightly indicating its well fermented.
mix the batter slightly and add salt to taste.