For the larded lung roast, first freeze the bacon briefly to make it easier to cut. Then first cut it into regular slices, which in turn are cut into strips of the same size, about 3 mm thick. Lard the beef loin along the grain using a larding needle (or poke holes with a long, pointed knife and insert the bacon strips into the holes). Rub meat well all over with salt and pepper.
Roughly chop root vegetables and onion and sauté briefly in oil in an (ovenproof) roasting pan. Add beef lung roast and sear briefly all around over high heat. Add bay leaf, peppercorns and remaining spices to the roasting pan, place in a well preheated oven and roast at 180-200°C for approx. 30 minutes, depending on the desired cooking level. Meanwhile, pour in some beef broth and baste the meat repeatedly with gravy. Lift out meat, wrap in aluminum foil and let rest warm for at least another 15 minutes.
In the meantime, pour off fat from the pan (or leave it in the pan) according to taste, sprinkle the drippings with flour and roast vigorously. Pour on some soup and boil everything well. Strain the sauce, stir in cream or crème fraîche and bring to the boil again. Season to taste with lemon juice. Carve beef lung roast and serve with the sauce.
The larded roast lung in cream sauce goes well with bread dumplings, Schupfnudeln or pasta as well as cooked fine vegetables (peas,