Clean, wash and chop the soup vegetables. Peel 1 onion and cut into slices. Wash the meat, dab dry and place in a freezer bag with the soup greens, onion wedges, bay leaf, clove, mustard and peppercorns.
Place in a bowl, add the red wine, port and 3/8 litres of water and bind firmly. Marinate for 1-2 days, turning occasionally. Place the roast on a sieve and collect the marinade.
Dab meat dry. Heat clarified butter in a roaster and fry the meat all around. Season with salt and pepper and lift out. Roast the soup greens