Prepare the meat
Remove the meat from the fridge approx. 30 mins. prior to cooking. Wrap 2 sprigs of rosemary around each medallion and tie with cooking string.
Pour the port over the plums, cover and leave to steep for approx. 30 mins. Drain the plums, retaining the port (approx. 150 ml). Melt the butter and sauté the shallot. Add the retained port and stock, bring to the boil, reduce the heat. Add the star anise and cardamom, reduce the liquid to approx. 200 ml. Strain the liquid, return to the pan and bring to the boil. Stir the cornflour into the hot liquid, cook for about another 1 min. Set aside the pan. Stir in the butter in batches. Add the plums, heat through, season.
Fry the meat
Heat the clarified butter in a frying pan. Season the meat, fry for approx. 3 mins. each side, remove, cover and leave to stand for approx. 5 mins. Serve the beef medallions with the spicy jus and the plums.