Rinse green gram and raw rice and soak them in 3 cups water for at least 5 hours.
Once they have turned soft, discard the water. Transfer them to a mixer/blender jar.
Also add in cumin seeds, roughly chopped ginger, curry leaves and green chilies (if using).
Adding 3/4 to 1 cup water, blend all the ingredients well to make a smooth batter.
Transfer the ground batter to a bowl and season it with salt (can be adjusted as per your taste).
Mix the batter well. It should be of normal dosa consistency, that is, a little less thick than a pancake batter. If it is too thick, pour in some water.
Heat a pan and grease it with oil. Once hot enough (check by splashing some water), pour a ladle full of the batter. Spread it as thin or thick as you like.
Drizzle oil or ghee over it, cover and cook. Let one side turn brown for a crispy texture, flip and cook the other side also if you like.
Take it off the tawa gently, and serve it with chutney or curry of your choice.