For the East Styrian must roast beef lard. Mix wine, must and soup. Place a large plastic bag (possibly freezer bag) in a bowl with the opening facing up.
Place beef in it, add root vegetables, pepper and spice corns and bay leaf and pour must mixture over it. Shake bag a little so that everything is covered by marinade. Seal bag and let marinate in refrigerator for three days. Move from time to time.
Remove meat from marinade (do not pour away must mixture!). Strip vegetables, pat meat slightly dry and brown on all sides in hot THEA. Place in a casserole dish with a thick bottom, add salt and enough of the must mixture to leave about 2 cm of liquid on the bottom.
Cook in the oven at 150 degrees for about 2 hours. Pour must mixture over the meat again and again. Remove meat and let rest wrapped in foil. Strain the meat juice with the vegetables, stir in the jam, season to taste and serve over the sliced East Styrian must roast.