Directions

1. In a stockpot, cover oxtails with 3 quarts water. Bring to a boil over medium-high heat. Reduce heat; simmer, uncovered, 15 minutes. Meanwhile, arrange onions and ginger on a baking sheet. Broil 4 in. from the heat until charred, 5-8 minutes, turning once. Peel off and discard charred skin from onion and ginger.
2. In a dry skillet over medium heat, cook and stir spices until fragrant, 3-5 minutes. Drain and discard water from oxtails; return oxtails to clean pan. Cover with 3 quarts water. Stir in onions, ginger, toasted spices, fish sauce, sugar, soy sauce and bay leaves. Bring to a boil over medium-high heat. Reduce heat; simmer, uncovered, 6 hours. While cooking, add water to keep oxtails covered with water.
3. Remove oxtails and set aside until cool enough to handle. Remove and discard bones. Set beef aside for soup or save for another use. Strain stock through a cheesecloth-lined colander, discarding solids. If using immediately, skim fat. Or, refrigerate 8 hours or overnight; remove fat from surface. Broth can be covered and refrigerated up to 3 days or frozen 4 to 6 months.
4. For the shrimp, in a shallow dish, combine oil, fish sauce, sriracha, lime zest and oregano. Add shrimp and stir to coat. Cover and refrigerate 45 minutes. Preheat oven to 375°. Drain and discard marinade. Arrange shrimp on a 15x10x1-in. baking sheet. Bake until shrimp turn pink, 8-10 minutes.
5. Meanwhile, prepare noodles according to package directions. Drain and rinse with cold water. In a large saucepan, bring stock to a boil. If desired, season stock with additional fish sauce, salt and pepper. To serve, add noodles and, if desired, beef to serving bowls. Cover with stock. Arrange shrimp and garnishes as desired.