Cut the ox-tails into pieces, separating them at the joints. Saute the onion and the ox-tails in the drippings to a delicate brown. Put the meat in the soup-pot with four quarts of cold water. Let it come to the boiling-point; add the vegetables and spices, and simmer for four hours, then add the salt. Strain, take off the grease. Select some of the pieces of ox-tail, one piece for each portion, and place them in the tureen with the soup. Ox-tails are gelatinous and make a smooth soup.