Dice onion, tomatillos, and jalapenos. You can leave seeds in or take seeds out of the jalapeno, depending on how spicy you want the chili. Smash and mince garlic cloves.
Preheat a large pot over medium heat and add oil. Add diced vegetables and saute until it's softened.
Add canned chopped green chiles and mix well.
Cut chicken breasts in half and nestle chicken halves into the vegetables. Cover the pot with a lid and cook for about 15 minutes. Flip chicken breasts and cook for a few more minutes.
Add beans, corn, chicken stock, and spices to the pot and mix well. Lower the heat to low and cover the pot with a lid.
Cook for about an hour.
Take chicken out of the pot and shred it using two forks. (If you want smaller pieces of chicken, you can also chop shredded chicken.)
Add chicken back to the pot and add sour cream. Mix well until sour cream is completely incorporated.
Serve with toppings like Monterrey Jack cheese, avocado, cilantro, squeeze of lime juice, crunchy tortilla strips, or some fresh jalapeno if you like it spicy.