Heat the oil in a pan over a medium high heat. (If you have a saute feature, do this right in the crockpot or instant pot.)
Once hot, add in the garlic and onion and saute until onions are translucent.
Add in the cumin, oregano, a little salt and pepper (about 1/2 tsp each) and stir to combine.
To a crockpot or instant pot, now add the chicken, beans, green chilis, broth, and onion mixture.
Stir to combine.
Set the crockpot to low for for 6-8 hours or high for about 4 hours. If using an instant pot, I'd do manual for about 20 minutes.
About 10 minutes before you want to eat, add in the sour cream and then shred the chicken right in the crockpot. Stir to combine. Taste and add more salt and pepper if needed.
Serve with fresh cilantro, avocado, extra sour cream and tortilla chips!