1. In a pan, cook the duck skin in a hot flame for 2 minutes. Turn it over and cook again for 1 minute. Put the fatty side of the duck down in the pan again and then add water to middle height of the meat and cook 10 minutes without turning over. Finely slice the duck.
1. While the duck is cooking, put all the ingredients for the sauce in a pan. Heat to a light boil and reduce the sauce by half. Strain the sauce and take off the heat.
1. Whip up the egg whites. Add the chocolate and cook in a small ramekin for 12 seconds in the microwave. Turn upside down tapping the ramekin to release the cake.
1. Pour the sauce onto the plate, and add the duck on top. Place the small cake on the same plate and garnish with kumquats or crystallized citrus fruits.