Microwave guajillo and ancho chiles until hot and pliable. Combine chicken stock, chicken breast, and chiles in a pot; boil, then simmer until chicken is cooked through.
Remove chicken, blend chiles with stock, then whisk in cream cheese and vinegar.
Shred chicken and discard skin and bones.
Heat oil, cook onion until softened, then add garlic and cook until fragrant.
Add corn, tomatoes, green chiles, black beans, and stock mixture; simmer. Stir in cheese, chicken, lime juice, and cilantro.
Serve immediately with avocado, cilantro, scallions, and cheese.
Notes
For a spicier soup, add more chiles or a dash of hot sauce.