In a large pot, heat the olive oil over medium heat. Add the diced onion and cook until translucent, about 5 minutes.
Stir in the minced garlic and diced bell pepper, cooking for an additional 2-3 minutes until softened.
Add the ground cumin, chili powder, smoked paprika, and cayenne pepper (if using). Stir well to combine and cook for 1 minute to toast the spices.
Pour in the black beans, corn, enchilada sauce, chicken broth, shredded chicken, and diced tomatoes. Stir to combine and bring the mixture to a simmer.
Reduce the heat to low and let the soup simmer for about 20 minutes, stirring occasionally. Season with salt and pepper to taste.
Serve hot, topped with shredded cheddar cheese, a dollop of sour cream, chopped cilantro, and tortilla chips on the side.