when u buy mangoes, if it is sour then u cannot eat it. Instead of throwing it u can prepare a delicious dish from that. U can mix with rice and eat this dish. It will be little sour, sweet, spicy .....ahh tasty.
Take mango's and remove the skin, mash it nicely (if u cannot mash in hand can grind in mixi)
Add jaggery, chilly powder and salt to mashed pulp. keep a pan on gas and put coconut oil, mustard seeds, hing, curry leaves. Finally add mixed pulp to it and boil it for 2-3 minutes. (if it is too thick you can add little water while boiling) serve it with rice. You can keep it for 2 days (no need of keeping inside the fridge).