Place oxtails (or short ribs) in a large soup pot, cover with water and bring to a a boil. Boil vigorously for 5 minutes, then drain. Rinse pot out well, rinse off oxtails, then place back in pot. Add 4 quarts water, star anise, cinnamon, cloves and peppercorns; bring to a boil. Scorch ginger and onions (see note 1 below) ; add to pot. Once water comes to a boil reduce heat to low and simmer gently, uncovered, skimming off foam, for about 3 hours./ Add more water as needed to keep oxtails covered. Add bottom-round roast and simmer until very tender, about 2 hours longer, adding more water as needed to keep meats covered. Remove roast and set aside to cool slightly. When cool enough to handle, slice the beef against the grain into paper thin slices. Set aside. Remove soup from the heat and remove oxtails; discard or reserve for another use. Line colander with a double layer of cheesecloth and strain broth through cheesecloth into a clean bowl. Let cool slightly, the refrigerate until thoroughly chilled, at least 2 hours. Skim fat from top of broth and discard. (Soup can be made ahead to this point. Store beef and broth in separate covered containers in refrigerator for up to 2 days, or freeze.) Shortly before serving, bring a large pot of water to a boil for blanching bean sprouts. Place broth in a large pot and bring to a simmer. Season with fish sauce. Simmer gently, partially covered, while preparing accompaniments. Place bean sprouts in a sieve or colander and immerse in boiling water for 20 to 30 seconds. Rinse with cold water; set aside to drain. Bring water back to a boil and drop in rice noodles. Cook just until softened but not mushy, 30 seconds to 1 minute. Drain and rinse with cold water; set aside. Divide noodles among 6 large bowls. Top with a generous pinch of been sprouts, a few shallots, several basil leaves, slices of cook beef and slices of raw sirloin or tender loin. Ladle hot broth over (the heat of the broth will cook the raw meat). Sprinkle with cilantro. Each guest should be provided with a spoon and a pair of chopsticks, as well as a small side plate with a generous pile of salt, another of black pepper beside it, and a lime wedge or two. Guests can squeeze a little lime juice, blend together salt and pepper in the proportion they wish, then use the mixture as a condiment for the beef slices. Set out small dishes of chiles, remaining herbs, shallots and bean sprouts. NOTE 1 -- To scorch ginger and onion -- If you have a gas burner, use tongs to hold ginger and onion pieces in the flame until charred. If you have an electric burner, heat a dry heavy cast-iron skillet over high heat. Add ginger and onion pieces and turn until blackened on all sides. NOTES : Recipe by Jeffrey Alford & Naomi Duguid Authors Note: In Vietnam, beef bones, unlike pork bones, are believed to need washing before using; the recipe starts the traditional way, with instructions for boiling the oxtails then discarding the water and starting to make the stock. Nutritional info by Eating Well Mag. 370 calories per serving; 13 grams protein, 4 grams fat (1.5 grams saturated fat), 70 grams carbohydrate; 850 mg sodium; 32 mg cholesterol; 1 gram fiber. Recipe by: Eating Well Mag. Jan/Feb 1997 Posted to EAT-LF Digest by Irene DiGiuseppe on Oct 31, 1998,