While the meats boil, char the ginger and onions individually. Utilize tongs to expose the piece of ginger and onion to an open flame on a gas burner. Rotate them until they acquire a light blackened appearance and a fragrant aroma (about 5 minutes). Remove charred skins thoroughly from both the ginger and onion (rinse them under the water if needed).
Add water to the stockpot and bring to a boil. Transfer the bones and meat back to the pot, along with the charred and cleaned ginger and onions. Add the scallions, fish sauce, salt and sugar.
Toast the spices (star anise, cloves, cinnamon stick, cardamom, fennel seeds, and coriander seeds) in a dry pan over medium-low heat for approximately 3 minutes, or until they become fragrant. Place the toasted spices in a piece of cheesecloth, then secure it by either tying a knot or using kitchen string. Add the spice bundle to the broth. If cheesecloth is unavailable, you can add the spices directly to the broth (they will be strained out at the end).
Lid the pot and let it simmer for an additional 4 hours. Sample the broth and fine-tune the seasoning by incorporating more salt, sugar, and/or fish sauce as necessary.
Strain the broth (saving the chuck pieces) and keep it warm
Cook the fresh or dry noodles based on the cooking instructions on the package or until they are slightly soft (they will continue cooking in the broth anyway).