Heat a wok adding oil, cumin seeds and curry leaves. Roast curry leaves along with cumin seeds till they turn crisp.
Transfer roasted ingredients in to a mixer, also include green chilly, salt and grated coconut with it. Finely grind them adding little water.
Shift the ground paste in to a bowl. Add buttermilk to it and mix well.
Heat a seasoning pan adding all the items under "seasoning ingredients" list in the order mentioned. When mustard seeds start spluttering add the seasoning to curry leaves tambli.
Cool, cool curry leaves tambli is ready. Serve it as side dish with rice and enjoy the goodness.
Note
You can substitute green chilly by pepper corns which gives it's own unique flavor. Make sure you roast them along with curry leaves and cumin.
Adjust consistency of tambli adding water or buttermilk. It should be thinner than regular chutney.
Fresh yoghurt is preferred for making tambli, do not use sour one.