Wash and soak moong dal for 15 to 30 minutes. Drain off the water from dal. Add dal, salt, ginger, chilies and cumin with little water to a blender jar and blend it (till smooth with a consistency similar to dosa batter. Do not add more water after the grinding is done. It has to be made to the right consistency while grinding).
Fry the onions and chilies in 1 tsp oil till lightly brown. Keep them aside.
Smear oil over a tawa and heat it. When it is smoky hot, sprinkle water and evaporate. Rub the pan with a piece of onion all over.
Pour one big spoon of batter and spread the batter to make a thin dosa.Sprinkle little ghee at the edges.
Flip and toast the dosa on the other side, flip it back and add onions and chilies. Toast on a low heat till it turns crispy.
Sprinkle water on the tawa, rub it with onion and repeat making next dosa. Serve moong dal dosa hot with your favourite chutney.
By Ria Samuel