- To a mixing bowl add corn rava. Add thick buttermilk to it. Mix well, the consistency will be runny. Keep covered for 5 mins.Then add salt and baking soda.Set aside. Heat oil and add the items listed under to temper.Now the mixture is a bit thick. Now add the tempering and mix well. Grease your idli plates with oil, take a laddle full of the batter and pour into the mould. Steam cook for 10 mins.Then its done. Turn off the flame and serve hot.