Dab meat dry and bind firmly in shape with kitchen string. Season meat with salt. Wash the rosemary and shake dry. Heat the oil in a large frying pan. Brown the meat on all sides.
Peel and roughly dice the onion. Remove meat from the roaster. Sauté onion in frying fat for 1-2 minutes. Dust with flour. Add wine while stirring and bring to the boil. Add roast meat and rosemary, except for two sprigs to garnish.
Add the stock and braise covered for about 2 hours. Turn every 30 minutes.
Meanwhile peel the turnips, leaving some green. Heat butter and sugar in a pan. Caramelise the turnips in this pan over medium heat until golden brown. Add to the roast about 20 minutes before the end of the stewing time.
Season the sauce with salt and pepper. Garnish with remaining rosemary.