Wipe the meat and trim off any skin and superfluous fat. Cut the meat into pieces suitable for serving and place in a dish with the vinegar. Leave for about 1 hr., turning 2 or 3 times; then drain well and dry. Cut the carrots and turnip into dice or Julienne strips for garnishing and keep the trimmings. Slice the onions. Heat the fat in a saucepan and fry the meat quickly until lightly browned, then remove from the pan. Fry the sliced onion until lightly browned; add the flour and cook slowly, mixing well, until a good brown colour. Add the water or stock and bring to the boil, stirring all the time. Replace the meat, add the vegetable trimmings and seasoning, cover with a fid and simmer gently for about 2½ hr. or until the meat is tender. Before serving, cook the diced carrots and turnip separately. Arrange the meat in the centre of a hot dish and pour the gravy over. Garnish with the drained, diced vegetables.