Soak, rice & urad dal as usual for idlis , then grind rice, adding cooked rice or sago or poha in the end, grind well.Then grind urad dal separately. Mix rice and dal batter well, add salt.
Allow to ferment for a minimum of 10 hours.Half an hour before cooking, add cooking soda, mix and then use. Actually in hotels they use this soda very liberally, so you may find more soft textured thatte idlis.
In Karnataka they use special thatte idli mould for preparing this idli.But i used idiyappam stand in my home... Those who have vadam stand in home can try with it.Those who don't have both, can try with plates having edges.
But my Idiyappam stand has no edges.If you use plate withe edges, you will get the exact look of Mysore idlis.Just cut a banana tree leaf, place over the plates, grease leaf with sesame oil, pour batter over the leaf and steam idlis.
Serve hot with coconut chutney, sambar, red chutney , if possible with crispy urad dhal vada to have the feel of eating in Mysore hotels.....:-)