Heat the oil in a heavy bottomed pan.Throw in the mustard seeds and let them splutter. Add the curry leaves at this time.
Reduce the heat to low and add the beans and turmeric powder and give it a quick stir. Close the pan and let the beans cook in the low heat.
Pulse the coconut and green chillies in a food processor (I use the small jar of the Indian mixer)
Once the green beans are tender, add the coconut mixture to it. Add salt and mix well. Serve with rice or rotis.
Notes
Sprinkle a little water to the pan and close it so there is some moisture to cook the beans, if you want it.I use freshly frozen grated coconut that you get in most Indian grocery stores. Break out a little and microwave for 30 secs before you grind it.