Prep all of your broth ingredients.
In a small fry pan on high, toast the onion and ginger until char marks appear. Once done, let them cool and remove any overly charred parts.
In a medium sized pot on medium high, combine the beef stock, chicken stock, salt, sugar and water.
Once the pot is boiling, add the beef chunks, charred onion and charred ginger.
Lightly toast the star anise, cinnamon and cloves in a fry pan until fragrant. Add to the pot and simmer partially covered for 30 minutes on medium low. Skim any scum off the top with a spoon as it forms while simmering the broth.
After 30 minutes, add the fish sauce to the pot. Check the seasoning of your soup and adjust according to your taste. It is recommended for the broth to be slightly more salty since the noodles and garnishes will dilute the seasoning.
If using beef balls, then add them to the stock to cook. If not, skip this step.
Prepare the dried rice noodles as per packaging. If using fresh rice noodles, then make sure they are soft first. If not, put it in the microwave and give them a minute or two. Then divide into bowls and blanch them in boiling water for 10 seconds and strain.