Place the beef in a pot and cook over medium heat until no longer pink. Drain the excess fat, and then add the onion, celery, bell pepper and garlic and cook, stirring occasionally, for 5 minutes. Add the remaining ingredients, except the ravioli, and bring to a gentle simmer. Gently simmer, partially covered and stirring occasionally, for 30 to 40 minutes, or until thickened and rich in colour. When the sauce is almost done, cook the ravioli as per package directions. Drain well, divide among plates or pasta bowls, top with bolognese sauce and serve. Sprinkle with freshly grated parmesan cheese, if desired.