Heat olive oil in a large Dutch oven or soup pot over medium heat.
Add the diced onion and cook for about 5 minutes, stirring occasionally, until softened.
Add garlic and cook for 30 seconds.
Stir in cumin, chili powder, smoked paprika, and oregano. Cook for about 30 seconds until fragrant.
Add the fire-roasted tomatoes with their juices, green chiles, chicken broth, and chicken.
Bring the soup just to a boil. Reduce the heat to a gentle simmer, partially cover, and cook for 15 to 20 minutes, or until the chicken reaches 165°F internally.
Transfer the chicken to a plate and shred it into bite-sized pieces using two forks.
Return the shredded chicken to the pot.
Stir in the drained black beans and frozen corn.
Simmer uncovered for another 7 to 10 minutes.
Season with salt and black pepper. Stir in 2 tablespoons of fresh lime juice, taste, and add more lime if needed.
While the soup finishes cooking, heat about ¼ inch of vegetable oil in a small skillet over medium-high heat.
Fry the tortilla strips in small batches for 1 to 2 minutes, turning as needed, until crisp and lightly golden.
Transfer the tortilla strips to a paper-towel-lined plate and season immediately with a small pinch of salt.
Ladle the hot soup into bowls and finish with crispy tortilla strips. Add avocado, cilantro, shredded cheese, sour cream, jalapeño, and fresh lime as desired.