Char the onion and ginger over an open flame or under a broiler until slightly blackened.
In a large pot, toast the star anise and cinnamon stick for 1-2 minutes until fragrant.
Add the beef bone broth, charred onion, charred ginger, and fish sauce to the pot.
Bring to a boil, then reduce heat and simmer for at least 20 minutes to infuse flavors.
While broth simmers, cook rice noodles according to package directions, then drain and set aside.
Strain the broth to remove the solids and return the clear liquid to the pot.
Place the cooked noodles in a large bowl and top with the raw, thinly sliced beef.
Pour the boiling hot broth over the beef to cook it instantly until tender.
Garnish with bean sprouts, cilantro, Thai basil, sliced chili, and a squeeze of fresh lime.