• 4 pounds beef soup bones (shank and knee)
• 1 medium onion, unpeeled and cut in half
• 5 slices fresh ginger
• 1 tablespoon salt
• 2 pods star anise
• 2 ½ tablespoons fish sauce
• 4 quarts water
• 1 (8 ounce) package dried rice noodles
• 1 ½ pounds beef top sirloin, thinly sliced
• ½ cup chopped cilantro
• 1 tablespoon chopped green onion
• 1 ½ cups bean sprouts
• 1 bunch Thai basil
• 1 medium lime, cut into 4 wedges
• ¼ cup hoisin sauce (Optional)
• ¼ cup chile-garlic sauce (such as Sriracha®) (Optional)

Preheat the oven to 425 degrees F (220 degrees C). Place beef bones on a baking sheet and roast in the preheated oven until browned, about 1 hour. Place onion halves on a second baking sheet and roast on another rack until blackened and soft, about 45 minutes. Transfer beef bones and onion halves to a large stockpot. Add ginger, salt, star anise, fish sauce, and 4 quarts water; bring to a boil. Reduce heat to low and simmer for 6 to 10 hours. Strain the broth into a saucepan and set aside. Place rice noodles in a large bowl filled with room temperature water. Let soak for 1 hour. Drain. When noodles have soaked for 1 hour, heat up the reserved broth by bringing it to a simmer. Bring a large pot of water to a boil. Cook the noodles in the boiling water for 1 minute. Drain. Divide noodles among 4 serving bowls; top with sirloin, cilantro, and green onion. Ladle hot broth over the top. Stir and let sit until beef is partially cooked and no longer pink, 1 to 2 minutes. Serve with bean sprouts, Thai basil, lime wedges, hoisin sauce, and chile-garlic sauce on the side.