Char onion and garlic. This can be done by placing ingredients on a baking sheet and under the broiler for about 5 minutes each side, until charred in spots, or over the flame of a gas stove, or in a sauté pan over high heat.
Place the cinnamon, anise, cloves, coriander, and cardamom in a saucepot and toast over medium heat until fragrant, about 2-3 minutes. Stir frequently to prevent burning.
Add charred onion, ginger, and chicken stock to pot, stirring to combine. Bring to a simmer and cover, reducing heat to medium low. Allow to simmer for about 30 more minutes to give the flavors a chance to infuse.
Strain the broth and discard the solids. Add soy sauce, fish sauce, rice vinegar, and brown sugar to broth. Taste and adjust seasoning as needed. Add in chicken and allow to heat thoroughly while making the noodles.
Cook the noodles according to instructions on packaging. Rinse with cold water once cooked and toss with a drizzle of neutral oil to prevent sticking.
Heat chicken according to instructions on packaging.
Add noodles to each serving bowl and top with broth and chicken. Top each bowl with desired garnishes.
