Dry roast star anise, cloves, cinnamon, and coriander seeds in a pot over medium heat until fragrant.
Char onion halves and ginger on a hot skillet until blackened to add a smoky flavor to the broth.
Combine spices, charred onion, ginger, broth, fish sauce, and sugar. Bring to a boil, reduce to simmer, and cook for 45 minutes to 1 hour.
Prepare rice noodles according to package instructions. Drain and set aside.
Slice beef or chicken thinly. For raw meat, the hot broth will cook it instantly in the bowl.
After simmering, strain the broth to remove solids. Return the broth to the pot to keep warm.
Divide noodles into bowls, add raw meat, and pour hot broth over it. Garnish with fresh herbs, bean sprouts, and lime wedges.
Add hoisin and Sriracha on the side for customizing.
