Fill a pot with water and boil the bones. Once boiling, drain and rinse. Re-fill the pot with water and boil the bones again.
Cut the onion into quarters. Peel the turnip and cut into large chunks. Peel the ginger and smash it with the flat side of a knife. Add the onion, turnip, ginger, peppercorns, and bay leaves to the pot.
Cover with water, and boil for 2 hours.
Add the spice bag. Boil for 1 more hour. Remove the spice bag.
Cook the noodles and add to serving bowls.
Boil the beef balls and flank steak in the soup broth, then place on top of noodles.
Add bean sprouts, lime juice, basil leaves, and soup broth. Eat.