Heat oil in a large pot over medium heat. Add onion and bell pepper, sautéing until softened, about 5 minutes.
Add garlic and jalapeño (if using), cooking for 1 minute. Stir in cumin and chili powder, toasting the spices for 30 seconds.
Pour in chicken broth and diced tomatoes with their juices. Bring to a boil, then reduce to a simmer.
Add black beans, corn, and shredded chicken. Simmer for 20 minutes to let the flavors meld together.
Stir in lime juice and season with salt and pepper to taste.
Ladle into bowls and let everyone top their own with tortilla strips, avocado, cheese, sour cream, cilantro, and extra lime wedges. Enjoy the colorful chaos!