Gather beef bones, onion, ginger, water, salt, sugar, fish sauce, star anise, cinnamon, cloves, coriander seeds, pho noodles, beef slices, bean sprouts, basil, cilantro, lime, and chili
Char the onion and ginger
Roast the star anise, cinnamon, cloves, and coriander seeds
Rinse the bones and blanch them in boiling water
Drain and rinse the bones again
Add bones, onion, ginger, spices, and water to a large pot
Simmer for several hours
Skim off foam and fat as needed
Season the broth with salt, sugar, and fish sauce
Soak or cook the pho noodles according to package directions
Place the noodles in serving bowls
Add raw beef slices on top if using
Ladle the hot broth over the noodles and beef
Top with bean sprouts, basil, cilantro, lime, and chili
Serve hot