Remove sausage meat from casings and, in a large heavy based saucepan, cook the sausage meat, the mince, onion and garlic over a medium heat until meat is well browned. Stir in crushed tomatoes, tomato paste, passata and water. Season with sugar, basil, fennel seeds, Italian herbs, salt, pepper and half the chopped parsley. Simmer, covered, for about 1½ hours, stirring occasionally.
Bring a large pot of lightly salted water to a boil. When boiling, cook the lasagna sheets for 8 to 10 minutes, until al dente, then drain and rinse in cold water.
In a mixing bowl, combine ricotta, egg, remaining parsley and 1/2 teaspoon salt.
Heat oven to 190 degrees C.
To assemble, spread 1 ½ cups of meat sauce in the bottom of a deep, greased 23 x 33cm baking dish. Arrange 6 lasagne sheets lengthwise over meat sauce and spread with half of the ricotta mixture. Top with a third of the mozzarella slices. Spoon 1½ cups meat sauce over mozzarella, and sprinkle with 1/4 cup parmesan cheese. Repeat layers, finishing with mozzarella and parmesan cheese and cover with foil. To prevent foil from sticking, either spray it with cooking spray, or make sure the foil does not touch the cheese.
Bake for 25 minutes, then remove foil, and bake an extra 25 minutes, or until the cheese is golden-brown. Allow to cool for 15 minutes before serving.