Cut beef into large cubes; remove fat and roll cubes in flour. Heat 2 tablespoons olive oil and 2 tablespoons butter in a large frying pan and sauté diced salt pork until crisp and brown. Remove pork from pan and transfer to a large earthenware casserole. Brown meat well on all sides in remaining fat, season to taste with salt and pepper and moisten with warmed cognac. Ignite cognac; let the flame bum away and add meat to casserole.
Coarsely chop carrots, leek, shallots, onion and garlic, and cook vegetables in fat remaining in frying pan, stirring occasionally, until they are lightly browned, adding a little more butter and olive oil, if necessary.
Transfer vegetables to the casserole with the meat; add the calf’s foot and bouquet garni. Pour over all but 4 tablespoons of the wine, and just enough hot water or good beef stock to cover contents of the casserole. Cover and cook in a very slow oven (280°F. to 300°F. Mark 1) for 1½ to 2 hours.
Remove fat from sauce; stir in, bit by bit, 1 tablespoon butter worked with 1 tablespoon flour; cover; continue to cook gently in the oven for about 2 hours or longer.
Brown onions in 1 tablespoon butter in a saucepan with a little sugar. Add 4 tablespoons red wine, cover and cook over low flame until onions are almost tender. Keep warm. Sauté mushroom caps in remaining oil and butter and a little lemon juice. Keep warm.
When meat is tender, remove calf’s foot and bouquet garni; correct seasoning; add onions and mushroom caps and sprinkle lavishly with finely-chopped parsley.