Heat olive oil in a large pot over medium heat. Sauté chopped onion and bell pepper for about 5 minutes until softened. Add minced garlic and cook for another minute. Stir in ground beef and cook until browned, about 6-8 minutes. Drain excess fat if necessary.

Sprinkle chili powder, cumin, paprika, salt, and black pepper over the meat mixture. Stir well and let cook for 2-3 minutes. Add diced tomatoes and beef broth, stirring to combine.

Add kidney beans and black beans to the pot. Bring to a boil, then reduce heat to low. Cover and let simmer for 30-40 minutes, stirring occasionally.

Taste and adjust seasoning if needed. Serve in bowls, garnished with fresh cilantro, sour cream, and shredded cheese if desired.