Idly is something I wake up to every morning. Its been my breakfast for almost 24 years. The batter is prepared either with idly rava or with rice. I shall post both the recipes.
At my in-law's place, we prepare the batter with idly rava. My MIL prefers fermenting the batter and adding the cooking soda and salt the next morning. So I too follow what she has been doing for years. :)