Take rava, rice flour and maida in a mixing bowl.
Add salt and water to it and mix
Mix to form smooth batter without lumps and keep it aside. Batter can be little thick now as we will dilute later
Finely chop the ginger, green chillies and onions.
Heat oil and temper with cumin, pepper and mustard.
Once it browns add the finely chopped onions, ginger and green chillies
Saute nicely for few minutes and garnish with curry leaves and coriander leaves.
Switch off the flame and transfer the contents to batter.
Add more water to batter to make it thin.
Heat kadai and spread the thin batter from edges and fill the gaps.
Drizzle oil and cook in low flame till it is golden and crisp.
Flip the dosa and cook for few seconds.
Serve onion rava dosa hot with chutney or sambar