Place the chicken in a large pot and season it with salt. Cover with water and bring to a boil. Add the onion and ginger. Add another generous shake of salt. Reduce heat and simmer for 35–45 minutes. Skim the surface of the broth occasionally to remove any scum or muck.
Remove the chicken from the pot and transfer it to a bowl. Once it's cool enough to handle, remove the skin, pick the meat from the bones, and shred it. Discard skin and bones or reserve them for another use.
Fish out the ginger and as much of the onion as possible and discard them both. Keep the broth on a low simmer.
Cook the noodles:
As the broth simmers, boil another pot of water and cook the noodles according to package instructions. Drain, rinse, and divide between bowls.
Finish the soup:
Return the chicken to the pot and bring it to a boil. Add the peas. Simmer for 5 minutes until bright green. Taste and season to your preferences.
To serve:
Ladle the broth over the noodles. Garnish to your preferences with fresh herbs, chili pepper, or sesame oil. Enjoy!
Notes
This recipe uses 6 cups of water which makes a very light broth for the noodles. If you like it soupier, add an additional 2 cups of water and adjust the seasonings to compensate.