In a medium pot, lightly char the ginger and cinnamon stick over medium heat for 2 minutes until fragrant.
Pour in the beef bone broth and add the star anise, sea salt, and black pepper.
Bring the broth to a gentle boil, then reduce heat and simmer for 15 minutes to infuse the flavors.
While the broth simmers, cook the rice noodles in a separate pot of boiling water according to package directions, then drain and set aside.
Slice the flank steak against the grain into very thin, translucent strips.
Place the cooked noodles in a large bowl and arrange the raw beef slices on top.
Strain the hot broth to remove solids, stir in the fish sauce, and immediately pour the boiling broth over the beef to cook it instantly.
Garnish with bean sprouts, cilantro, Thai basil, and a squeeze of lime.