Preheat the oven to 350°F and prepare a 9×13 baking dish.
Slice zucchini or summer squash with a cheese slicer into thin slices. Sprinkle lightly with salt and set aside to drain in a colander.
Prepare meat sauce. Cook ground beef and black pepper in a large skillet. Add green pepper and onion, cook and stir until meat is no longer pink. Stir in tomato paste, sauce and wine, basil and oregano. Bring to a boil and simmer for 20 minutes.
Combine 1 egg, ricotta cheese, and parsley in a bowl.
Assemble lasagna. Pour half of the meat sauce into the bottom of the prepared pan. Then layer half of the summer squash slices, half the ricotta mixture, followed by all of the mushrooms, then half of the mozzarella cheese. Repeat by layering the remaining meat sauce, summer squash slices, ricotta mixture and mozzarella. Spread Parmesan cheese evenly over the top. Bake for 45 minutes or until golden and bubbly. Let stand for 5 minutes before serving.