Mix both the flours and add salt and 1 1/2 cups water (to make a thin batter). Add the crushed cashewnuts and coconut (khopra) to it and mix well.
For tempering, heat ghee in a small kadai, add cumin seeds to it. As soon as the cumins crackle, add asafoetida and green chillies. Fry for a few seconds and then add this tempering to the batter. Mix the batter well.
Now heat a non stick tava and put little batter on the tava in a circular manner. Put little oil in the holes of the dosa. Cook until crisp.
Serve hot with coconut chutney.
Adding cashewnuts and coconut (khopra) is optional.