First, wash the beans add salt and microwave it for 6 to 7 mins in water keep aside. Now grind coconut and green chilli. Make a tadka of mustard seeds urad dhal curry leaves and hing. Add all (beans coconut and tadka) to the idli batter. Grease an idli plate and add the batter and steam it for 12 mins. Serve with idli powder or chutney.