Parboil the bones. Place bones in a large pot, cover with cold water, and bring to a strong boil for 10 minutes. Drain and rinse bones to remove impurities. Rinse the pot.

Char the aromatics. Over an open flame or under a broiler, char onion halves and ginger until blackened in spots. This adds depth and a slight smokiness.

Toast the spices. In a dry pan, toast star anise, cinnamon, cloves, cardamom, and coriander until fragrant, 1–2 minutes. Tie in cheesecloth or use a spice ball if you like.

Simmer the broth. Add cleaned bones back to the pot. Cover with about 5 quarts of water. Add charred onion, ginger, toasted spices, and optional daikon. Bring to a gentle simmer and cook uncovered for 3–4 hours, skimming foam and fat occasionally.

Season. Strain the broth. Stir in fish sauce, sugar, and salt to taste. The broth should be savory, lightly sweet, and aromatic. Adjust until balanced.

Prep the beef. For paper-thin slices, partially freeze the beef for 30–45 minutes, then slice against the grain. Keep chilled until serving.

Cook the noodles. Soak or boil rice noodles according to the package until just tender. Rinse briefly to stop cooking and prevent sticking.

Heat the broth to a boil. It must be very hot to gently cook the thin beef in the bowl.

Assemble. Divide noodles into bowls. Top with raw beef slices (and cooked brisket, if using). Ladle over the boiling broth to cook the beef. Finish with scallions and cilantro.

Garnish at the table. Serve with basil, bean sprouts, lime wedges, chili, hoisin, and sriracha. Let everyone season to taste.