In a large pot over medium heat, cook and stir chicken in the oil for 5 minutes. Add the garlic and cumin and mix well. Then add the broth, corn, onion, chili powder, lemon juice, and salsa. Reduce heat to low and simmer for about 20 to 30 minutes.
Break up some tortilla chips into individual bowls and pour soup over chips. Top with the Monterey Jack cheese and a little sour cream.