Combine the garlic, oregano, salt and pepper in a large bowl. Add the pork tenderloin pieces and toss to coat. Add the olive oil to a large pot or dutch oven on the stove over medium high heat.
Add the pork and sear on each side for 1-2 minutes. Add the onion, carrot and celery. Sauté with the pork for 2-3 minutes. Pour the beef broth, red wine, tomato paste and diced tomatoes over the pork and stir to combine. Add the bay leaf and sprig of rosemary. Cover and simmer on the stovetop for 15 minutes.
Remove from the heat and place in the Wonderbag to slow cook for 6-8 hours. Remove the pot from the Wonderbag, uncover the pot and remove the bay leaf and rosemary sprig. Remove the pork from the sauce and use a fork to shred the meat. Serve the meat over pasta or polenta, topped with sauce from the pot. Top with parmesan cheese.
Serve the meat over pasta or polenta, topped with sauce from the pot. Top with parmesan cheese.