Heat olive oil in a large skillet over medium-high heat. Working in batches, sear the beef cubes on all sides until browned, about 6-8 minutes total. Transfer to slow cooker.
In the same skillet, sauté the onions and bell peppers until softened, about 5 minutes. Add garlic and cook for another minute. Transfer to slow cooker.
Add the black beans, pinto beans, crushed tomatoes, tomato paste, beef broth, and chopped chipotle peppers to the slow cooker.
Stir in the chili powder, smoked paprika, cumin, brown sugar, salt, and pepper. Mix everything together until well combined.
Cover and cook on low for 8-10 hours or on high for 4-5 hours, until beef is tender and flavors have melded together.
Serve hot with cornbread, shredded cheddar cheese, sour cream, and diced jalapeños on the side.