Char the onion and ginger over an open flame or under a broiler until slightly blackened to release deep aromatics.
In a large pot, simmer the beef bone broth with star anise, cinnamon, charred onion, and ginger for 20 minutes.
While the broth simmers, prepare the rice noodles according to package directions, then drain and set aside.
Slice the raw beef eye of round into paper-thin strips against the grain for maximum tenderness.
Strain the broth to remove the solids and return the liquid to the pot, seasoning with fish sauce, salt, and pepper.
Divide the cooked noodles into bowls and top with the raw beef slices.
Pour the boiling hot broth directly over the beef to cook it instantly in the bowl.
Garnish with bean sprouts, cilantro, Thai basil, jalapeño slices, and a squeeze of fresh lime.