Prepare the noodles by soaking them in room temperature water for 20-30 minutes.
If you have a disposable tea bag or sachet, place the whole coriander (if using), cloves, star anise and cinnamon stick in one.
In a medium pot on high heat, add beef broth, onion, ginger, sugar, ground coriander (if using), 1 tablespoon fish sauce, salt and spice bag.
Bring the soup to a boil and turn the heat down to low and simmer for 20 minutes.
In a large pot, bring half a pot of water to boil. When read to eat, place one serving of the noodles in a sieve and plunge into the boiling water to blanche for about 5-10 seconds. Immediately drain and place in a serving bowl. Repeat with the second serving.
Garnish the noodles with the meat slices, onion, green onion, cilantro and bean sprouts.
Adjust the flavour of the soup by adding more fish sauce and/or salt. Turn the heat back up and bring it to a rolling boil. If you are using the meatballs, they can be cooked in the soup.
Ladle over the serving bowl of noodles with hot soup. The soup has to be hot enough to cook the meat slices.
Serve with Thai basil, chili peppers, lime, hoisin sauce and Sriracha sauce.