Chop the onion and optionally mince some cilantro; set both aside.
Shred or grate the cheese and keep it ready.
Warm 2 tablespoons of avocado oil in a large pot over medium heat. Season the chicken with salt and pepper, add it to the pot, and cook until browned and cooked through, about 5 to 7 minutes. Remove and set aside.
In the same pot, toss in the diced onion and garlic; cook until soft and fragrant, roughly 3 to 4 minutes.
Mix in the ground cumin chili powder and ground coriander, and let the spices bloom for about a minute.
Add the diced roasted tomatoes and cook until they start breaking down and blending with the spices, approximately 3 to 4 minutes.
Pour the enchilada sauce into the pot, stir well, then add the chicken broth and return the browned chicken to the pot.
Include the drained black beans and corn, bring the mixture to a boil, then lower the heat and simmer for 15 to 20 minutes to develop flavors.
Remove the pot from heat and stir in the sour cream until everything is smooth and creamy.
Add the shredded cheese gradually, stirring until it melts fully and the soup turns creamy.
Taste and season with more salt and pepper if needed, and add a little lime juice if you enjoy a tangy touch.
Serve the soup in bowls and garnish with any of the toppings like tortilla strips avocado cilantro extra cheese or lime wedges as desired.