In a heavy skillet, cook ground beef and pork sausage with the onion, garlic and green pepper until the meat is cooked through., about 15 minutes. Drain and transfer the mixture to a stockpot. Add the green beans, zucchini, tomato sauce and canned tomatoes. Season with Italian style seasoning, salt and pepper. Bring to a boil then reduce heat and simmer for 1/2 hour. Serve hot topped with a sprinkle of Parmesan cheese.