Soak green gram for 3 to 4 hours or overnight. They get doubled up in volume after soaking, so it will be 1 cup now.
Method
Grind the soaked and drained green gram along with green chillies and rice flour. Add required water while grinding to get it in to dosa batter consistency.
Transfer the batter to a container, add salt and mix well. Meanwhile heat a dosa griddle, smear some oil and get it ready. Pour a ladle full of batter at the center of the griddle and spread in circular motion like dosa. Cook until done and flip it over.
When both sides of green gram dosa is cooked to perfection, using flat spatula remove and serve with coconut chutney.
Notes
Soak the gram for good 3 to 4 hours otherwise the batter wouldn't be perfect.
You can sprout the green gram and then grind too. It will be more healthier.
Do not add much water while grinding, the batter would turn running. In that case you cannot spread it over griddle.