Preheat oven at 350. In a ovenproof skillet heat a shadow of oil on high heat. Generously salt and pepper both sides of the duck breast. When the skillet is hot, add the duck skin side down. Cook until the skin is golden brown, about 5 minutes, turn to the other side and cook for 3 minutes. Turn again, skin side up, discard all of the fat from the pan and place in the hot oven. Cook for another 10 to 15 minutes.
Remove from the oven and cover with aluminum foil to keep warm.
Meanwhile in a separate small sauce pan place the dried cranberries and the tangerine juice. Cook over medium heat until the cranberries have softened and the juice is reduced.
Lower the heat and add the mascarpone. When the mascarpone is melted and the juice starts to thickens, remove from the heat. With an immersion hand-held mixer, puree the mascarpone, tangerine-cranberries sauce until nice and smooth. Add less than a tablespoon of the juices from the duck. Mix well. Return the pan to the heat and warm for a minute or so.
Spread the sauce on the bottom of the plate and serve the duck sliced over it.