Method:
Mix rava and rice flour together with the buttermilk. Add water to bring it to dosa consistency. Don't make it too thin or watery.

Then grind the ginger and green chillies and add this paste to the batter. Add salt to taste.
Chop the onions finely and keep aside. Heat aflat pan and make thin dosas and sprinkle the chopped onions and little jeera seeds over the dosa with oil each time.

Remove from pan after they are nicely done and look crisp. You can have with sambhar and chutney.