Heat the oil in a pan. Sauté the asparagus for approx. 2 mins., remove and set aside. Bring the stock to the boil in the same pan. Stir in the polenta, reduce the heat, simmer over a very low heat for approx. 30 mins., stirring frequently. Return the reserved asparagus to the pan and simmer for approx. 10 mins. until a thick paste has formed. Stir in the butter and tomatoes.
Remove the meat from the fridge approx. 30 mins. prior to cooking. Preheat the oven to 60°C, warm the platter and plates. Mix the butter, Gorgonzola and rosemary, season. Heat a little oil in a frying pan. Fry the meat all over for approx. 3 mins., season, cover and leave in the frying pan for approx. 3 mins. Plate up the fillets with the polenta on the warmed plates and finish with the Gorgonzola butter.