01 - Heat a large skillet over medium-high heat. Add beef in batches if needed, searing until browned on all sides. Transfer to the slow cooker. If using ground beef, brown and crumble before transferring.
02 - In the same skillet, cook onion, red and green bell peppers for 3-4 minutes until softened. Add garlic and cook 1 more minute. Transfer mixture to the slow cooker.
03 - Add drained beans, diced tomatoes with juice, beef broth, tomato paste, chili powder, cumin, smoked paprika, cayenne, oregano, salt, and black pepper to the slow cooker. Stir well to combine all ingredients.
04 - Cover and cook on LOW for 6-8 hours or HIGH for 3-4 hours, until beef is tender and flavors have melded together.
05 - Taste and adjust seasonings as needed. Serve hot, garnished with your favorite toppings such as shredded cheddar cheese, sour cream, chopped cilantro, or sliced jalapeños.