It is claimed to have developed by the chefs of MTR during the world war II. Due to shortage of rice at that time, this was experimented and devised as an alternative recipe in place of the regular idli. For those not familiar with MTR - Mavalli Tiffin Center, is a very famous and ever crowded Veg Indian restaurant in Bangalore.
They are known for their Rava Idli and Bissibella Baath. Also their instant ready-mix of various food items are so popular among the common crowd.