Sprinkle pork with salt and pepper; transfer to a 4-qt. slow cooker. Add carrots, celery and onion. In a small bowl, whisk broth and tomato paste; pour over vegetables. Add plums, garlic, bay leaves, rosemary, thyme and, if desired, olives. Cook, covered, on low 5-6 hours or until meat and vegetables are tender., Discard bay leaves, rosemary and thyme. If desired, sprinkle stew with parsley and serve with potatoes.