After trying different proportions, I happened to strike this proportion, which has been very successful consistently.
This requires a grinder for the dough – one can try in the mixi, decreasing rice by 1 cup.
I always use Venpuzungal arisi or I R 20 or kaar arisi.
One can try with Ponni puzungal arisi.
Since, in my experience, once the dough is refrigerated, the texture of idli definitely changes, I make idlis as soon as the dough is freshly fermented .
It is better to refrigerate idlis than the dough !
Boiled Rice - 4 cups
Urad dhal - 1 cup
Aval (not very thin, but atleast medium) - 1 cup
Methi seeds - 1 tsp
Mix all the above, wash well 2,3 times.
Soak in 6 cups of water (4+1+1) for atleast 6-8 hrs.
Do not discard the soaked water – use that for grinding.
Roughly drain before grinding – you need 6 cups of water to be used during grinding.
This amount will slightly vary with the quality of rice – you can determine it in 2,3 times.
Grind all ingredients together, using the entire measured water, gradually adding in small quantities.
Grind very fine & add salt at the end.
Transfer the dough from grinder to a tall vessel,mix thoroughly once using your hands ( this is important).
Allow to ferment – sometimes it takes 12 hrs for the fermentation to start.
Give maximum 24 hrs, not more than that.
Before making idlis, do not stir the dough.
Usually rice is ground separately to a coarse texture & hence settles down – so stirring used to be done.
Here the texture is uniform & stirring will disturb the spongy texture of the fermented dough.
Steam idlis as usual.
The rest of the dough, after refrigeration wll give very good dosas.
It takes 2,3 times of trial to determine the amount of water you need.
The quantity of water does determine the texture of idlis.
Small nuances like using the soaked water for grinding, measuring the water used, not disturbing the dough once the fermentation is complete - I feel, help in giving “feathery idlis”.
Once you get it right,”idli-haters” in your family will become “idli-lovers”.
Serve with chutney & sambar.