Add the Pot Mixture ingredients to the Instant Pot, in the order listed. Secure the lid, making sure the vent is closed. Using the display panel select the MANUAL function*. Use the +/- keys and program the Instant Pot for 12 minutes. When the time is up, quick-release the remaining pressure. Carefully remove the chicken from the pot to a cutting board and shred, then return to the pot and stir. Serve in a bowl topped with sour cream, diced tomatoes, shredded Mexican-blend cheese and diced avocados.