Score the skin: Using a sharp knife, score the skin in a cross-hatch pattern (try not to cut the meat).
Marinate the meat: overnight or longer, max. for 2 days. Prepare a small pot - the meat should be almost completely submerged in the marinade, you can also use a thick ziplock bag. Whisk the ingredients for the marinade (red wine, honey, soy sauce, vinegar, jam, and spices), bring them to boil then leave to cool. Add the duck breast, skin-side up, cover, and put in the fridge.
On the second day: Preheat the oven to 212°F / 100°C.
Sear the meat: it's best to use an oven-proof pan but if you don't have such pan, just use a regular skillet then transfer the meat to a small baking dish.Remove the meat from the marinade, pat dry thoroughly with paper towels. Place in a cold (!) pan, skin-side down. Turn on medium-low heat and cook for a couple of minutes or until the skin is browned and the fat rendered. Don't cook it over too high heat, the fat needs to be rendered slowly. It's good to weigh the meat down so that the skin that be browned uniformly - you can place a loaf pan on top of the meat and put an olive oil bottle on top to weigh it down. Turn the breast on the other side and cook briefly, until the meat is browned. Leave a tablespoon of fat in the pan and discard the rest.
Bake: Place the duck breast in a small baking dish (I used a 20 cm/8-inch oven-safe pan). Pour in the marinade. Cut the plums in half, remove the stones, arrange them around the meat. Place the dish in the oven.
Bake in a preheated oven for about 55-60 minutes or less, to your desired doneness. After this time the duck should be around 150°F (66°C). It should come to the 'well-done' temperature (160°F/71°C) while resting. If you prefer your duck breast medium, bake it for about 45 minutes, to 60°C / 140°F. Medium-rare is 52°C / 125 °F . The baking time will depend on how long you’ve seared the meat in the pan and how big your duck breast is (it's best to use a grill thermometer to measure the temperature!*).It’s important to cook the meat to a temperature and not to time, you can measure internal temperature with an instant thermometer (stick it into the thickest part of the meat). Well-done duck breast (safe for kids to eat) should be cooked to a minimum internal temperature of 71°C / 160°F. Remember that after removing the meat from the oven, its internal temperature will continue to rise.
Remove the dish from the oven. Transfer the meat to a plate, cover it tightly with aluminum foil, and leave to rest for 5-10 minutes.
Prepare the sauce: If the plums are very soft, remove them from the sauce, but leave harder fruits in (very soft plums will fall apart completely while reducing the sauce). Cook the sauce for about 5 minutes over medium heat until thickened. Discard cardamom capsules, star anise, and cinnamon stick.
Serve: Cut the duck breast into thin slices against the grain*, pour the sauce over, serve with cooked rice and roasted plums. Optionally, sprinkle with coriander leaves and sesame seeds.