Add oil to the Instant Pot. Using the display panel select the SAUTE function and adjust to HIGH or MORE.
When oil gets hot, put the onion in, cut side down. Cook without moving until the onions begin to char, 4-5 minutes. Remove the onions to a bowl.
Add the Spice Mixture ingredients to the pot. Cook and stir for one minute or until spices are fragrant.
Add warmed water to the pot and deglaze by using a wooden spoon to scrape the brown bits from the bottom of the pot.
Add the remaining Pot Mixture ingredients and the reserved onions and their juices. Turn the pot off by selecting CANCEL, then secure the lid, making sure the vent is closed.
Using the display panel select the MANUAL or PRESSURE COOK function*. Use the +/- keys and program the Instant Pot for 20 minutes.
When the time is up, let the pressure naturally release for 10 minutes, then quick-release the remaining pressure.
Carefully remove the meat from the pot to a cutting board. Remove skin and shred meat; discard bones and skin.
Strain the broth and return to the pot. Turn the pot off by selecting CANCEL, then select the SAUTE function.
Bring the broth to a simmer and cook the rice noodles in the broth according to the package directions.
Serve noodles and broth over chicken. Garish as desired.
Notes
*The MANUAL and PRESSURE COOK buttons are interchangeable