Heat ghee and fry vermicelli and rava for around 5-6mins. Let them cool to room temperature.
Add curd and keep it aside for around 1/2 an hour. If the vermicelli and rava soaks well, the idlis come out very soft. Add more curd if the batter becomes too dry.
Add coconut, salt, coriander leaves and green chilies (cut into small pieces). Heat oil and add mustard seeds and urad daal when mustard starts popping and urad daal becomes brownish, add curry leaves, baking soda and a pinch of asafoetida. Add this seasoning to the batter and mix well.
Put the batter in greased idli stand and steam them.