Marinate the duck with 1 tsp ginger paste, ½ tbsp mustard oil and a little salt, refrigerate for at least 1-2 hours, even better if it is overnight.
Add the remaining oil to a pan, when smoking hot, throw in the crushed green cardamom, cinnamon and bay leaves, allow the spices to splutter.
Now add the sliced onions, saute till the onions change colour. Stir in the garlic paste and remaining ginger paste, continue to sauté, some 3-5 minutes.
Add the marinated duck, sprinkle the turmeric powder, cumin powder, red chilli powder and salt, give it all a hearty stir.
Cook over a medium flame stirring occasionally till oil starts to separate from the masala.
Add 1/2 a cup of warm water, bring to a gentle simmer.
Transfer to a pressure cooker. Cool over a medium flame, 4 whistles I would reckon. Allow the steam to release on its own.
Now gently pour the coconut milk, throw in the whole green chilies and beresta, cook over a medium flame for another 10-15 minutes till the gravy thickens.
Adjust seasonings, serve hot.