Heat instant pot to saute. When hot, add group-1 ingredients and saute for 2-3 minutes.
Press cancel, add group-2 ingredients, give a good stir, close and lock lid (making sure the valve is set to seal). Let cook for 6 minutes on manual (or pressure cook) and then let it be for about 10 to 15 minutes on warm mode.
Release pressure, open lid, transfer only chicken on to a plate. Set Instant pot to saute and let soup come back to a boil. In the mean time shred chicken (discard bones if using chicken thighs with bones).
Once it comes to a boil, add all group-3 ingredients and shredded chicken (along with any accumulated juices). Let boil for 1-2 minutes, until spinach wilts.
Take off heat and let soup stand for a few minutes before serving. Ladle into bowls or let cool and pack in mason jars for later use. (Soup will thicken lightly as it cools)
Notes
1. Salt will depend on the type of chicken stock used and your taste preference. I used 33% less sodium chicken stock and used ½ teaspoon salt which was perfect for my taste. 2. I used a 3-quart Instant pot to make this soup.