In a big pot, heat the olive oil over medium heat. Add the onion and bell pepper, sautéing until soft.
Stir in the garlic, cooking for one minute until fragrant.
If using raw chicken, add it to the pot and brown on all sides, about 5 minutes. If using rotisserie chicken, shred and add later.
Add chicken broth, black beans, diced tomatoes with green chilies, cumin, chili powder, salt, and pepper. Stir well and bring to a simmer.
Let the soup simmer for 20-25 minutes. Check chicken internal temperature reaches 165°F if cooking raw chicken.
If raw chicken was used, remove it, shred it, then return shredded chicken to the pot. Adjust seasoning as needed.
Serve the soup hot, garnished with fresh cilantro, squeeze of lime, and crispy tortilla strips for crunch.