Wash and Peel the skin of the mangoes. Dice them into big chunks and add them to a thick bottom cooking vessel.
Add 2 cups of water, turmeric powder and cook the mangoes on medium flame for atleast 10 minutes or until the mangoes are slightly mushy.
In the meanwhile, take a mixer grinder jar and add grated coconut, green chillies and cumin seeds. Add few spoons of water and grind it to a thick consistency.
Whisk the 3/4th cup of curd and keep aside. There should be no lumps.
Once the mangoes have cooked, add the ground coconut paste and mix well. Ensure the gas flame is low. This Curry should not boil and bubble too much else it loses taste.
Now add the whisked curd and a tsp of jaggery along with salt to taste. Mix well once.
Switch off the flame as soon as you see that the yogurt has mixed with the curry and prepare for tempering.
In a small tempering pan, heat coconut oil, add mustard seeds, methi seeds, red chillies and curry leaves. Once the mustard crackles, pour the tempering over the curry, mix well and serve immediately with rice and a dry vegetable of your choice.