In a large bowl combine the meat, carrots, celery root, leeks, onions, honey, allspice, cloves, ginger, garlic, bay leaves, rosemary, thyme, cinnamon stick, red wine, balsamic vinegar, white wine vinegar, Worcestershire, soy sauce, 2 tablespoons salt and 1 tablespoon pepper. Marinate, covered, in the refrigerator for 5 days.
Preheat the oven to 325 degrees F; position an oven rack at the second-lowest height.
Remove the meat from the marinade and sprinkle with salt and pepper. Strain the vegetables through a sieve, reserving the marinade and vegetables separately.
Heat the clarified butter in a roasting pan and then brown the meat vigorously on both sides. Add the reserved vegetables and continue to cook until you have a nice caramelization on the meat and vegetables. (This step is important for the color and flavor of the gravy.) Add the marinade to the roasting pan and cover everything with aluminum foil.
Bake until the meat is tender, 3 to 4 hours.
Set the roast on a carving board and wrap it in aluminum foil. Strain the cooking liquid through a fine-mesh sieve into a saucepan and boil down to about 500 milliliters/2 cups.
Mix the cornstarch with 2 tablespoons cold water, then add to the sauce. Boil the sauce to thicken.
Slice the roast and serve with the sauce and vegetables or with braised red cabbage and dumplings.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.