Soak rice noodles in boiling water for 5 minutes.
Thinly slice beef and onion.
Pour water into a pot and add beef for broth, onion, ginger, and whole peppercorns. Bring to a boil.
While the broth is simmering, prepare the toppings (bean sprouts, cilantro, lime, etc.).
Place the cooked rice noodles in a bowl and pour the broth over them.
Add sliced beef and various toppings to finish.