Wash the beans, and string them. Trim off both ends of each bean and then finely chop the beans. If there any beans which are a bit mature, shell them and discard the pods.
If you are using the microwave to cook your vegetables, like I do, then cook the beans till they're done. And then proceed as described below.
In a pan, heat the oil (coconut oil gives an authentic flavour and taste) and add the mustard seeds. When they splutter, add the black gram lentils and sautxe9 till they brown. Now add the curry leaves, stir once and add the beans. Stir fry the beans for a couple of minutes, then add half a cup of water. Add the salt and turmeric powder and bring to a boil. Turn down the heat and allow the beans to cook till done and the water has evaporated completely.
If you microwaved your beans, then add the beans where mentioned above. Just don't add the water for cooking. Sprinkle a handful of water, add the turmeric powder and salt and make sure the beans are well coated and seasoned and sautxe9 till the little water there was has evaporated completely. Take the cooked beans off the heat.
Now run the grated coconut and the green chillies in the jar of your mixer grinder, a couple of times, without adding any water. You will have crushed mixture of the coconut and chillies, with flecks of the green chillies showing. Do not grind to a paste.
This crushing releases the flavours/ juice in the coconut and the chillies. Add this to the beans and stir well to mix.
Serve warm with rice, a vegetable in gravy preparation like sambhar, rasam or pulissery.