Wash mangoes well then peel the skin.If you are using big mangoes slice it in to small pieces.
Add the peeled mangoes in to a curry chatty or cooking vessel, then add chili powder,turmeric powder and salt.Add one cup of water and cook the mangoes covered over medium flame for 10-15 minutes
Mean time grind the coconut and cumin seeds in to a smooth and fine paste.keep it aside.
Then add the yogurt/curd in to a blender and blend well.you can use 1 1/2 cup or 2 cup of yogurt depends on how much gravy you need.
Once the mangoes cooked well add ground coconut in to it.stir well and let it boil.
once boiled reduce the flame and add blended yogurt in to the curry and mix well,keep on stirring.Cook in a low flame for few more minutes .Don’t let it boil.switch off the stove stir few more minutes otherwise the curd will separate.
Then heat coconut oil in another pan, once the oil become hot add mustard seeds.when mustard starts to splutter add red chili and curry leaves, fry well then add this to the curry,immediately cover the pot with a lid.