In a large pot, heat 2 tablespoons of olive oil over medium heat. Add the chopped yellow onion and diced jalapeño. Sauté for about 5 minutes until the onion is translucent.

Add the minced garlic, dried oregano, and chili powder, stirring continuously for 1-2 minutes until fragrant.

Pour 4 cups of chicken broth into the pot and add the chicken breasts. Season with salt and pepper. Bring to a boil, then reduce heat and simmer uncovered for 10-15 minutes.

Once the chicken is cooked through, carefully remove it from the pot and shred it into bite-sized pieces. Return to the pot.

Stir in 1.5 cups of sour cream and 0.5 cup of Monterey Jack cheese until melted. Add 2 cups of frozen corn and heat through for 3-5 minutes.

In a small bowl, whisk together 3 tablespoons of cornstarch with 3 tablespoons of water until smooth. Pour into the pot, stirring continuously until thickened.

Remove from heat, and stir in the juice of 1 lime and 0.5 cup of chopped cilantro. Adjust seasoning as necessary.

Ladle the warm chili into bowls, offering optional toppings like crumbled cotija cheese or avocado slices.