In a large pot, combine the beef broth, water, onion, ginger, fish sauce, sugar, star anise, and cinnamon stick. Bring to a boil over medium-high heat, then reduce to a simmer. Let it simmer for about 30 minutes to allow the flavors to meld.

While the broth is simmering, cook the rice noodles according to package instructions. Drain and set aside.

After 30 minutes, strain the broth to remove the solids. Return the liquid to the pot and keep it warm over low heat.

In a separate skillet, quickly sear the thinly sliced beef over high heat for about 1-2 minutes until just browned.

To serve, place a portion of cooked rice noodles in a bowl, top with the seared beef, and ladle the hot broth over the top.

Garnish with fresh basil, cilantro, lime wedges, sliced jalapeños, and bean sprouts. Serve with hoisin sauce and Sriracha on the side for added flavor.