Cut Drumsticks and boil them with water (just to immerse in it) with Turmeric powder, Coriander powder and Chilli powder
Meanwhile grind Coconut, shallots and cumin seeds coarsely with little water and keep it aside.
When Drumsticks are half done, add sliced raw mango pieces and salt.
Add grinded coconut paste and allow it to be cooked further.
For Tempering, In a pan add coconut oil, mustard, curry leaves, small onion and saute till onion turns transparent and crisp.
When drumsticks are done, add the tempered ingredients to curry and serve.