Soak green gram and rice together for 9-10 hrs in enough water.
After that grind with onion, ginger and green chillies.
Add salt at the end of grinding.
Heat oil and fry cumin seeds, green chillies with diced onions for 2- 3 , for the topping.
Keep seperately in another plate.
Heat a heavy dosa pan.
Pour dosa by spreading from the centre.
Add a teaspoon of oil around the dosa.
Sprinkle the topping and press with the flat ladle.
Fry in medium flame till the dosa becomes crisp.
Fold and serve hot with chutney.