Choose thin young beans without bulges; avoid yellow matured beans they will be too fibrous. Cut them into 2 inch pieces.
Heat coconut oil in a pan, when it's hot add mustard seeds, whole red chili, and curry leaves. When you put the curry leaves in be prepared for a lot of spluttering. You can put a lid on right afterward for a few seconds to prevent all the mustard seeds from popping out and to protect yourself from splattering oil. You can add some sliced shallots or onions and crushed garlic at this point if you like but it's not necessary at all as the beans will be quite flavorful as it is.
Set heat to low and stir in the cut beans.
Mix in turmeric, red chili powder, green chili, and salt.
Cook on low with the lid on stirring occasionally to make sure it doesn't stick to the bottom.
When it's almost done cooking, take the lid off and stir fry until the beans are fully done. Enjoy!