OPTIONAL: in recent years, I've started to slice the onion down the room, remove the paper and char it along with the sliced ginger on a baking sheet in the oven under the broil setting. This will take 5-10 minutes but you do the at your own risk, keeping a close eye to keep the onions and ginger from burning. Once cooled use in step #3.
Toast:Heat the instant pot on the saute setting. Drop the whole spices listed under 'spice ball' and toast for 2-3 minutes, stirring frequently or until fragrant. Place spices in a cheesecloth bag or mesh spice ball. This makes it easy to remove later. Add the halved onions and ginger root to the pressure cooker and allow them to sear for 6-8 minutes (if you skipped the optional step above.) You want to flip them once or twice about halfway through.
LOAD: Pour in 8 ½ cups of water. Using a wooden spoon, scratch the bottom of the pot to help loosen up all the brown bits left behind. Add chicken, spice ball, fish sauce, 1 tablespoon of sugar, and salt.
PRESSURE COOK: Cover the instant pot; seal the vent. Cook on manual high pressure for 25 minutes and do a quick release. When the instant pot says there are 2 minutes of cooking time left, prepare an ice water bath (lots of ice in a large bowl with cold water.)
CHICKEN: Remove the chicken to the ice water bath. Skim any scum from the surface of the broth. Strain the broth into a large pot or measuring cup. Rinse out the instant pot insert, then pour the broth back in. Allow the broth to simmer on the saute setting if you want to concentrate the flavor a little more.
ADJUST: Taste and adjust with additional sugar or salt to taste. Remove the skin from the chicken and shred or slice the chicken while the broth is simmering.
ASSEMBLE: when ready to serve, place about 2-3 ounces of noodles in a bowl, top with chicken and ladle on the broth. Serve the herbs and sauce on a plate and allow everyone to top their bowl as desired!