- Prepare broth: In a stockpot on medium-high, heat oil. Add yellow onion and sweat until onion is translucent, about 5 minutes. Add garlic, ginger and five-spice, stirring until fragrant, about 1 minute.
- Add broth, tamari, hoisin, star anise and cinnamon; bring to a boil then reduce to a simmer for 1 hour, 15 minutes, skimming off foam as it simmers.
- Strain broth through a cheesecloth-lined mesh sieve and return to stockpot. Add bok choy and mushrooms and return to a boil.
- Into 4 bowls, divide noodles. Divide hot broth with mushrooms and bok choy over the noodles.
- Garnish with bean sprouts, basil, cilantro, green onions and chile. Serve with lime wedges and hoisin on the side (if using).