Place the onion and ginger directly over a gas flame or under a broiler until charred and fragrant.
In a large pot, combine the beef bone broth, charred onion, ginger, star anise, sea salt, and black pepper.
Bring the broth to a boil, then reduce heat and simmer for 20 minutes to infuse the flavors.
While the broth simmers, cook the brown rice noodles according to package instructions, then drain and set aside.
Strain the broth to remove the solids and return the clear liquid to the pot, adding the fish sauce.
Divide the cooked noodles into bowls and top with the raw, thinly sliced eye of round steak.
Pour the boiling hot broth over the beef to cook it instantly, then garnish with bean sprouts, Thai basil, jalapeño, and a squeeze of lime.