Slice ginger, garlic, onions and chillis finely. Mix all the other spices together with a little water to make a paste. Joint the duck and fry in a little oil until golden brown. Remove from heat and set aside. Fry the onion, ginger, garlic and chillis in a large saucepan until light brown. Add the duck and spice paste then cook for 15 minutes, stirring all the time. Add vinegar, salt, and if required, a little water. Cover and simmer till duck is cooked and gravy thick.