Preheat the oven to 200°C. Pat the meat dry with paper towels. Salt the meat all over. Quickly brown in a little oil, turning constantly. Place half of the hay in a cast-iron roaster (with a lid). Sit the meat on top. Place the rest of the hay on top so that the meat is completely covered. Pour in the wine and stock. The meat must be approx. 3/4 covered with the liquid. Put the lid on and place in the centre of the oven. Heat for 10-15 mins. until the liquid is simmering. Then reduce the temperature to 120°C. Braise the meat for 2-3 hrs. Shortly before serving, strain 200 ml of liquid into a small pan for the sauce. Add the butter while stirring, simmer briefly. Slice the meat and serve with the sauce and Knöpfli.