In a medium pot, combine the beef bone broth, sliced ginger, star anise, cinnamon stick, and sliced yellow onion.
Bring the broth to a gentle boil, then reduce heat and simmer for 15 minutes to allow the aromatics to infuse the liquid.
While the broth simmers, cook the brown rice noodles in a separate pot of boiling water according to package directions, then drain and set aside.
Thinly slice the flank steak against the grain into very thin strips and season with sea salt and black pepper.
Remove the ginger, star anise, and cinnamon stick from the broth using a slotted spoon and stir in the tamari.
Place the cooked noodles in a large serving bowl, top with the raw beef slices, and pour the boiling hot broth directly over the beef to cook it instantly.
Garnish the bowl with fresh bean sprouts, Thai basil leaves, and a squeeze of lime before serving.