1. Roast the beef bones, onion, and ginger in the oven at 400°F for 30 minutes.
2. Transfer the roasted ingredients to a large pot and cover with water. Bring to a boil, then reduce to a simmer.
3. Add star anise, cinnamon, coriander seeds, sugar, fish sauce, and salt. Simmer for 90 minutes.
4. Strain the broth and return it to the pot. Add the beef brisket and cook until tender, about 45 minutes. Remove and slice thinly.
5. Cook the rice noodles according to package instructions. Drain and divide among bowls.
6. Top the noodles with sliced beef sirloin, brisket, and ladle the hot broth over. Serve with bean sprouts, lime wedges, fresh herbs, and chili peppers.
Notes
For a richer broth, simmer the bones for at least 3 hours.