Thinly slice the eye of round beef against the grain and set aside in the refrigerator.
Char the onion and ginger over an open flame or under a broiler until blackened in spots to release their fragrant oils.
In a large pot, combine the beef bone broth, charred onion, ginger, star anise, and cinnamon stick.
Bring to a boil, then reduce heat and simmer for 20 minutes before seasoning with fish sauce, sea salt, and black pepper.
While the broth simmers, cook the rice noodles according to package directions and drain.
Strain the broth to remove the solids and return the clear liquid to the pot, keeping it at a rolling boil.
Divide the cooked noodles into bowls and arrange the raw beef slices on top.
Pour the boiling broth over the beef to cook it instantly, then garnish with bean sprouts, Thai basil, jalapeno, and a squeeze of lime.