In the kanchipuram temple, the idlis are steamed in cylindrical bamboo baskets called kudalai, lined with mandarai leaves, each a foot long. A number of these baskets are cooked at a time in huge pots. Since they're cooked in kudalai, they're also called kudalai idli. The typical cook time is rougly 2-3 hours. But at home, cooking in idli moulds, it takes just about 15 minutes. These, as other idlis, are a wonderful travel food and stay unspoiled at room temperature for a couple of days.
They are then cut into discs for distrubuting as prasadam to the temple visitors. As cooking experience goes, making this idli for some reason gives me great pleasure and satisfaction.
My bouncy batter:
Making of Kanchipuram Idli at Varadaraja Perumal Kovil