GermanFoods.org provides a recipe for traditional German oxtail soup made with oxtail, vegetables, white wine and spices. About.com offers a similar recipe with red wine, cream and flour for a unique twist.
To make traditional German oxtail soup, brown 2 1/4 pounds of oxtail pieces in oil in a large pot. Stir in three chopped onions and then add one diced celery root, one chopped leek, one diced carrot, two halved cloves of garlic and 2 teaspoons of tomato paste. Season with two bay leaves, one or two thyme twigs and 1/2 teaspoon of peppercorns. Allow the vegetables to cook briefly and then add 1 1/4 cups of dry white wine and 8 1/2 cups of hot water. Simmer on low heat for two and a half hours.
After simmering, remove the oxtails and strain the broth through a fine sieve. Return the meat and broth to the pot and remove from heat. Add 1/2 cup of middle dry sherry to the soup and season to taste with salt, black pepper and cayenne pepper. Serve the soup garnished with parsley.
To make About.com's recipe, use the same basic ingredients and process, but discard the vegetables when straining the broth and use a dry red wine instead of the white wine. Cool the broth and skim the fat before finishing the soup. Remove the meat from the bones and chop into bite-sized pieces before adding seasonings and sherry. Add cream mixed with flour just before serving.