Heat the olive oil in a large pot or Dutch oven over medium heat. Add the chopped onion and cook until soft, about 5 minutes.
Add the minced garlic, cumin, chili powder, and oregano. Cook for 1 minute until fragrant.
Stir in the shredded chicken, Rotel tomatoes, black beans, corn, and chicken broth. Bring the mixture to a simmer.
Reduce the heat to low, cover, and let the soup cook for 15 minutes to allow flavors to combine.
If making the creamy version, stir in the heavy cream and heat through for 2 minutes; do not boil after adding cream.
Stir in the shredded cheese until it melts into the soup. Season with salt and pepper to your taste.
Ladle the chicken tortilla soup into bowls. Top each serving generously with crispy tortilla strips and your choice of additional toppings.
Notes
For crispy tortilla strips, cut corn tortillas into thin strips and bake or air fry until golden brown.
If you prefer a spicier soup, add a dash of your favorite hot sauce when simmering.
This recipe is a great candidate for slow cooker chicken tortilla soup; combine all ingredients except cream and cheese in the slow cooker and cook on low for 4 hours. Stir in cream and cheese at the end.