Clean and cut the duck. Mix the 3 powders into a thick fine paste and keep it for 15 min. Heat oil in a pan and add mustard seeds. When it starts spluttering add the above prepared paste. Stir it well in low flame till it becomes dark in colour. Heat oil in another pan and add onion, ginger, garlic, chilly, salt and curry leaves. When it turns light brown,add the above prepare powder mix into it and saute well. Add duck, vinegar and little water into the onion and mix well. Cover the lid and cook . After cooling down ,add coconut milk and boil again for a few minutes.