Clean the duck breasts and fry on a well-heated pan till a golden crust is formed. Put the pre-cooked pieces into a thick-walled pot and pour hot water on top so that it covers two thirds of the duck. Crush the berries together with the sugar and starch and saute in a frying pan for 2-3 minutes. Then add it to the poultry, salt and pepper to your taste and cook on a mid-low heat for 25 minutes.