In a large stockpot cook the beef mince and pork mince, pepperoni, green capsicum, red capsicum, garlic, onion, carrots and celery. Cook until beef is no longer pink. Drain into a large colander to drain grease.
To the large pot add the mushrooms, tomato sauce, tomatoes, tomato paste, stock cubes, bay leaves, thyme, oregano, basil, chilli flakes, black pepper, sugar and beef stock and stir well. Pour the meat mixture into the pot. Bring to a boil, reduce heat and cover. Simmer for 2 hours.