Preheat the oven to 200°C/gas mark 6 and put a medium baking tray inside. Heat the redcurrant jelly, red wine and star anise in a shallow-sided pan over a low heat. Add the plums and simmer rapidly for 5 minutes, then reduce the heat and simmer for a further 10 minutes, until the sauce is syrupy. Discard the star anise.
Meanwhile, rub the Chinese five-spice into the scored skin of the duck breasts. Place the duck breasts skin-side down in a frying pan over a medium heat and allow the skin to crisp slowly for 6-7 minutes.
Transfer the duck breasts to the preheated baking tray, placing them skin-side up, and cook in the oven for 5-6 minutes. Remove and rest on a warm plate for 5 minutes. Meanwhile, cook the noodles in boiling water for 4-5 minutes until tender, adding the pak choi for the final minute. Drain, then toss through the sesame oil and soy sauce. Slice the duck and serve with the plums, sauce, noodles and pak choi.