In the days of yore, oxtails were from oxen, but nowadays they are from the tails of cows. This delightfully robust soup is making a comeback on American menus. A comfort soup, known to generations of the past, is becoming a curiosity to younger patrons. The usual soup suspects, onions, carrots, celery, and thyme, make up the remainder of the soup broth, with some options such as wine or tomato added for extra flavor.