Peel and finely chop the onion and garlic. Clean the carrots and cut into small cubes. Cut the celery into not too thin slices, then heat 1 tablespoon of olive oil in a roasting pan. Add the chopped pork belly, fry in it until crispy and remove. Put the minced meat in the roaster and stir-fry vigorously. Add onions and garlic and sauté briefly. Deglaze with the can of tomatoes and red wine and stir in the tomato paste. Add the pork belly, add 1-2 teaspoons of oregano, season with salt and black pepper. Let the whole thing simmer for about 30 minutes with the lid closed.
In the meantime, cook the spaghetti or other noodles al dente. Then put this in a large bowl, spread the minced meat sauce over it, sprinkle with parmesan and serve.