Set Instant Pot to Saute.
Once the IP is hot, add the oil.
Add the diced onion and minced garlic and cook for 1-2 minutes, stirring occasionally.
Add the cubes chicken and cook until no longer pink on the outside, stir occasionally. About 3 minutes.
Add salt, pepper and red pepper flakes. Stir to combine.
Add chicken broth.
Add uncooked pasta to the pot and gently push it using a spatula or wooden spoon so its evenly distributed and submerged in the liquid.
Add 1/2 cup of water over pasta.
Cover and seal the lid. Make sure the valve points to Sealed. Change setting to manual and adjust time to 4 minutes on High Pressure.
Once Instant Pot beeps to show that it's done, wait 4 minutes and after that do a quick release, by changing the position of the valve to Vent. Carefully remove cover and stir.
Remove the lid and set IP to Sauté.
Add the frozen veggies and sour cream, stir to combine. Cook for about 2 minutes.
In a small bowl mix cornstarch and water until fully combined and add to the pot. Gently stir to combine and cook for 1-2 minutes, until it thickens.
Turn off the Instant Pot.
Serve topped with chopped parsley.
When reheating of the stove top, either add some milk, cream or broth, to make it creamier.