Preparation Heat peanut oil in heavy large pot over medium-high heat. Sprinkle oxtails with salt and pepper. Add oxtails to pot and brown on all sides, about 20 minutes. Transfer oxtails to large bowl. Add onions and next 6 ingredients to same pot. Sauté until vegetables are tender, about 8 minutes. Return oxtails to pot. Add 12 cups water, beef broth and 3 tablespoons fish sauce. Cover and simmer gently until oxtails are very tender, about 3 hours. Using tongs, transfer oxtails to large bowl. Strain broth into another large pot; discard solids. Remove meat from oxtails; discard bones. Add meat to broth. Refrigerate overnight. Spoon solid fat off top of soup. Cook noodles in large pot of boiling salted water until tender. Drain; rinse under cold water. Return to same pot. Toss noodles with sesame oil. Bring soup to boil. Divide noodles, sprouts and next 6 ingredients among 6 bowls. Ladle soup into bowls. Serve with lime wedges and additional fish sauce. *Available at Asian markets and some supermarkets nationwide.
Preparation Heat peanut oil in heavy large pot over medium-high heat. Sprinkle oxtails with salt and pepper. Add oxtails to pot and brown on all sides, about 20 minutes. Transfer oxtails to large bowl. Add onions and next 6 ingredients to same pot. Sauté until vegetables are tender, about 8 minutes. Return oxtails to pot. Add 12 cups water, beef broth and 3 tablespoons fish sauce. Cover and simmer gently until oxtails are very tender, about 3 hours. Using tongs, transfer oxtails to large bowl. Strain broth into another large pot; discard solids. Remove meat from oxtails; discard bones. Add meat to broth. Refrigerate overnight. Spoon solid fat off top of soup. Cook noodles in large pot of boiling salted water until tender. Drain; rinse under cold water. Return to same pot. Toss noodles with sesame oil. Bring soup to boil. Divide noodles, sprouts and next 6 ingredients among 6 bowls. Ladle soup into bowls. Serve with lime wedges and additional fish sauce. *Available at Asian markets and some supermarkets nationwide.