Place potatoes, onion, celery, and carrots in bottom of slow-cooker. Pour in chicken broth and sherry. Season pork all over with salt and black pepper, sage and garlic and herb seasoning. Place pork on top of vegetables and top with Parmesan, pressing the cheese into the meat. Cover and cook on low for 6 to 8 hours or high for 3 to 4 hours.
Toast the pine nuts in a small skillet over medium heat until golden brown, about 2 to 3 minutes. Arrange watercress on salad plates. Top with pear slices, goat cheese and toasted pine nuts. Drizzle with olive oil and sherry vinegar. Slice pork crosswise into 1/2-inch thick slices. Serve 1/2 of the pork with this meal and reserve second half for another recipe. Serve all of the vegetables from slow-cooker and the brothy sauce with pork.