Place chicken into a large stock pot and fill with enough cool water to cover the chicken. Bring to a boil on high heat, then immediately discard the scummy water and rinse the chicken until cool. Drain then set the chicken aside.
Select the saute function to preheat your Instant Pot and wait until the "hot" indicator turns on.
Pour the oil into the pot and swirl to coat evenly.
Place the onions, ginger and garlic into the pot and allow the onions to char for 4-5 minutes each side.
Move the ingredients aside to make room for the chicken. Place the chicken into the pot and sear each side until slightly brown (optional). Please also refer to Note 1.
Add the fish sauce, water and sugar (See Note 3).
Place the cinnamon stick, star anise and coriander into a spice bag. Tie the spice bag to ensure spices do not get loose, then place the bag into the pot (See Note 2).
Close the lid and turn the steam valve into sealing position.
Cancel the saute function and select pressure cook, at high pressure, for 30 minutes.
While the Instant Pot is preparing the broth, cook the rice noodles according to package instructions and place them into 3 bowls. If you plan to use any optional accompaniments, this is also a good time to wash/prepare them.
When the broth is ready, unplug the Instant Pot and allow it to naturally release the pressure, or do a quick release. Please ensure that the float valve is completely down before you open the lid.
Allow the chicken to cool and atop your noodles with your cut of choice. Serve the noodles and chicken in the broth, with optional accompaniments. Enjoy!