Soak mung bean overnight in water. Drain, wash and rinse. Cook it in pressure cooker until one whistle.
In a large bowl, add rice flour and curd, mix well. Set aside for about 10 mins
Now add water, coconut, cumin, ginger,coriander leaves, salt, cooked mung and mix well. It will be moist and sticky.
Grease the pan, spread the dough on the pan slowly to form a thin layer. or If you have used paper/foil, then flip and place it on the pan with batter facing the pan.
Heat the pan, close the lid and cook for about 2 mins. Continue cooking until the bottom of the rotti has turned golden brown, smear oil/butter to avoid dryness and flip it.
Cook the other side for couple of mins. When the brown spots appear, take it off the pan, serve hot with butter and chutney