2) Meanwhile, bring a large pot of salted water to a boil. Add the linguine and cook until al dente, stirring occasionally, about 8 minutes. Drain, reserving 240ml of cooking liquid. Add the linguine to the ragu and toss to coat, adding some reserved cooking liquid to moisten. Transfer the pasta to a large serving bowl. Sprinkle with Parmesan and serve.
3) For the marinara sauce: In a large casserole pot, heat the oil over a medium-high flame. Add the onions and garlic and saute until the onions are translucent, about 10 minutes. Add the celery, carrots, and 1/2 teaspoon each of salt and pepper. Saute until all the vegetables are soft, about 10 minutes. Add the tomatoes and bay leaves, and simmer uncovered over low heat until the sauce thickens, about one hour. Remove and discard the bay leaf. Season the sauce with more salt and pepper, to taste. (The sauce can be made one day ahead. Cool, then cover and refrigerate. Rewarm over medium heat before using.)
Yield: 2 litres