Peel mangoes and cut them into six pieces each. Heat 45 ml oil and season with mustard seeds. When they crackle, add curry leaves , lemon grass , cinnamon , cloves, spring onions, garlic , ginger and red chillies. Saute for five minutes.
Add the mango pieces , vinegar , sugar , chilli powder and turmeric powder. Stir well. Add a little water. Mix well. Cover and simmer till the mango is done and dry. Keep aside.
Heat the remaining oil in another pan and roast vegetable curry powder until brown.
Gradually add the coconut milk and stir well. Add mango mixture and mix gently. Add salt to taste.
Lower the heat and bring to a boil. Simmer till the gravy thickens. Serve with rice.