(in some different locale it is likewise called 'aviri kudumu): Soak dark gram dal, without husk for two hours. Granulate it into fine glue including next to no water. Include enough salt.
Take a wide mouthed vessel and empty clean water into it (half filled). Bind a perfect material to the vessel as appeared in the image underneath. Take player around five-six idlis amount and pour it on the material and spread it. Put the vessel on low fire and steam it until back of a spoon tells the truth out from it(without any player adhering to it). Poli rotti is presently prepared. Best backup for this is coconut chutney.