Sweat the onion, carrot, celery and garlic in the oil until soft, about 10 minutes.
Add the pancetta and fry for another 5 minutes. Now the parsley and cook out for a minute or so.
Now the lentils and chopped tomatoes, along with a tin full of water and the stock, too. Add the bay leaves and bring to the boil. Simmer for about 30 mins, covered, until the lentils are cooked.
Add the pasta and cook, uncovered, for about 10 minutes. Season and serve.