Soak the idli rava in water. The waters should just cover the rava. do not add more water. Let this soak for 4-5 hours.
Soak the urad dal in water and if adding poha or methi seeds add that too.
Soak the idli rava first and let it soak for 4 - 5 hours.
Urad dal can be soaked separately for an hour. It is enough.
I grind in the grinder. But my friend told me you can do it in the mixie too.
Drain the water from urad dal and grind the urad dal (methi+poha,if using) into a smooth paste using enough water in between.
The batter should be smooth and fluffy and not very thick or grainy.
Add this to a big wide bowl or box.
Take out the soaked idli rava and drain some excess water, gently squeezing it.
Add it to the ground urad dal.
Mix it well with the urad dal. Let it get mixed evenly, then only you will get soft idlis.
Add salt to this and mix well. Let it ferment for 8 hours. Mine will always get fermented in 6-7 hours, still, I don't know how and why!!!, irrespective of the weather. So generally I grind either during the day or if I happen to grind in the night, I will do it around 11 pm.
Else it will over-ferment and make the idlis sour.
Before fermentation, the batter should be in a flowy consistency, as shown in the picture.
Once the batter is fermented, mix it well and grease the idli moulds and por the idli batter on the moulds and steam it for 8 minutes (or till the idlis get cooked)