Wash and cut the duck. Heat oil in a pan. Add onion paste, ginger-garlic paste, cumin and garam masala powder and salt, stirring continuously. Add a little water to keep the spices from burning. Cook for 2 minutes or until the oil separates from the spices. Add the duck pieces and mix well. Stir and cook on high heat. Now add 1 cup of water and cook it until the oil separates. Gradually stir in the coconut milk. Cover and cook on low heat until tender. Add fried onion and stir well. Add garam masala powder, roasted cumin powder and green chillies. Cover and cook for another 10 minutes on low heat. Turn off the heat, sprinkle the fried onion and serve hot with plain rice, rice flour roti or paratha.