In a large skillet, heat the oil over medium heat. Add onion and bell pepper. Let cook, stirring occasionally, until onions become soft.
Add the garlic, cumin, and chili powder. Mix well to combine the spices. Cook for about one minute.
Add the ground meat (beef and pork), salt, and black pepper to the pan. Using a wooden spoon, break up the meat and incorporate it with the vegetables and spices. Let cook until all meat is brown.
Carefully transfer the meat mixture to a slow cooker. Add beans with their juices, corn, tomato sauce, diced tomato with their juices, and jalapeño. Discard the jalapeño seeds if you don't want the Chili to be too hot. Stir to combine.
Cover and cook for about 6 hours on high or 8 hours on low. Taste and season with salt as needed.
Serve with cheese, sour cream, and scallions.