Heat half of the oil in a large pan. Cut the ribs into thirds with a sharp knife and add them to the pan.
When the ribs are brown, remove them from the pan, add the rest of the oil and soften the carrots, celery and onion.
When the vegetables are softened, return the ribs to the pan and pour over the stock. Bring to the boil and simmer on a low heat for three hours.
Cook the pasta according to packet instructions in a pan of boiling salted water until tender. Drain well.
When the three hours have elapsed, pick out the rib bones and discard. Serve with the cooked pasta.