Spray a 6-quart or larger slow cooker with cooking spray. Add vegetable oil to a large skillet and heat over medium heat. Season the ribs with salt and pepper. Add the ribs to the pan and sear until lightly browned on all sides, working in batches if necessary. Transfer the ribs to the slow cooker.
Once the leftover ribs have cooled, transfer them into an airtight container and store them in the fridge. Enjoy the remaining ribs for 3 to 4 days.