Heat the butter or oil in your Instant pot using the saute function on normal for approximately 2 minutes. Add in the diced onion and minced garlic and briefly saute for another 1-2 minutes or until garlic and onion becomes fragrant.
Mix in the chili powder, paprika, and oregano. Deglaze the pot with the lime juice. Press cancel on the Instant pot to turn off the saute function.
Add in the green chilis, red kidney beans, chicken, and chicken broth. Give a quick stir and make sure chicken is slightly or completely submerged in the broth (don't push the chicken to the bottom of the pot). Place the lid on the Instant pot and set to pressure cook on manual high pressure for 8 minutes. Make sure you set the valve on the top to sealing. *See note if you are wanting to use frozen chicken.
Do a quick release of the pressure once the cooking time has elapsed. Remove the chicken from the pot and shred in a separate bowl using two forks (or use a hand mixer**). Return the shredded chicken to the instant pot.
Turn the saute function back on the instant pot. In a separate bowl (preferably a pyrex measuring cup) whisk the corn starch with ½ a cup of the milk until well combined. Add the corn starch milk, remaining milk, sour cream, and corn to the instant pot. Cook on the saute function for another 3-4 minutes, stirring consistently to thicken the chili. Add salt to taste.
Top with shredded cheddar cheese and/or cilantro as desired. Store in airtight container in the fridge for up to 4 days. Freeze for up to 6 months.