In a heavy bottom pan, heat half of the coconut oil and sear the duck pieces on both sides in batches. Keep aside.
In the same pan, add the remaining coconut oil and add the mustard seeds. Allow to splutter and then add the fenugreek seeds, curry leaves, green chillies, ginger and garlic.
Cook on medium heat for a minute and then add the onions. Mix and sauté till the onions are light brown and then add the turmeric power and black pepper powder. Mix well and add the duck pieces. Season with salt and add 400ml coconut milk.
Mix well to combine, cover partially and cook on low heat till the duck pieces are tender. Check occasionally and if the gravy feels thick, add some water (not too much though!).
Add the coconut cream and the tomato pieces; check and adjust seasoning. Simmer for another 2 minutes and remove.
Garnish with curry leaves.