Soak chana dhal for 2 to 3 hours.
Wash n chop beans to small pieces.
Grind the soaked chana dhal, green chillies, hing, coriander leaves, grated coconut to a coarse paste without adding water .
In a kadai add oil, mustard seeds , once it crackles add curry leaves n then the chopped beans n cook it .
Add the ground paste n cook again till the beans is cooked well .
Note: The ground paste has to be coarse n let there be few whole grains of dhal as it gives the best flavour to the recipe