Slice the carrots and onions, and put them in a saucepan with the salt beef, the herbs, bayleaves and enough warm water to cover. Bring to the boil, add the peppercorns and simmer gently till the meat is tender, allowing from 25 to 30 minutes to the pound. When done, remove the meat from the pan and let it stand till quite cold. Then cut it into very thin slices, removing all fat. Pour a little aspic into a mould and, when nearly set, lay a few slices of the beef on it, decorate with thin slices of beetroot, cut in fancy shapes, thin slices of hard-boiled eggs and a few sprigs of parsley. Cover with a little jelly and continue with alternate layers till the mould is filled. Put in a cold place or on ice and, when set, turn out carefully and serve with a mustard sauce.