Soak idli rice overnight in water.

Soak whole black gram with fenugreek too overnight.

When u grind, grind black gram with fenugreek first.

Once that is ground fine, add your idly rice and cooked rice(preferably leftover rice) and grind everything into a batter.

Keep Idly-Dosa Batter overnight in a warm place to ferment.

Add salt before making idlis or dosas.

:- Make idlis in the first two days of grinding a batter and dilute the batter a bit when u make dosas. :- For idlis, batter should be thicker than ketchup consistency wise.