Heat the canola oil in a large skillet over medium-high heat. Season the pork with salt and pepper and brown it on all sides, 2 to 3 minutes per side. While the pork is browning, add the celery, carrots, and onion to the bowl of a slow cooker. Put the pork on top of the vegetables and add the tomatoes and garlic. Place into the slow cooker and cook on low for 6 to 8 hours.
Remove the pork to a cutting board or sheet pan. Pour the vegetables and liquid from the slow cooker bowl into a saute pan over medium heat, and mash with a fork. Add the tomato paste to the pan sauce and stir to incorporate. Shred the pork, add it to the vegetables, and let this simmer, uncovered, while you cook the pasta (save 2 cups of the ragu for the Round 2 Recipe Lasagna Roll Ups).
Bring a large pot of salted water to a boil. Add the penne, stir, and cover the pot. When it returns to a boil, remove the cover and stir it again. Cook until the pasta is al dente, about 8 minutes. (Save 1 cup of pasta for the Online Round 2 Recipe Savory Noodle Pie.) Put the pasta into a serving platter, and pour the ragu over top. Serve immediately, garnished with basil leaves and Parmesan.