Bring a large pot of salted water to a boil. Cook the lasagna noodles for 2 minutes less than the time indicated in the package directions. Rinse with cold water then drain and set aside.
Spread 1/4 cup of the sauce on the bottom of a 9-by-13-inch baking dish.
In a medium bowl, whisk the egg with the ricotta, 1/4 cup of the Parmesan, the Italian seasoning and salt. Add the vegetables and 1/2 cup of the mozzarella and stir to combine. Spread 1/3 cup of the mixture on each of the 9 noodles and roll up each one, starting from a short side. (You can roll the noodles on an oiled baking sheet if they stick to your work surface.)
Place the lasagna rolls seam-side down in the baking dish. Top with the remaining 1 1/4 cups sauce, 1/2 cup mozzarella and 1/4 cup Parmesan.
Cover the dish with foil and bake for 30 minutes. Uncover and bake until the cheese is golden brown and bubbly, about 15 minutes. Remove from the oven and let rest 5 to 10 minutes before serving.
Weelicious Tomato Sauce:
Heat the olive oil in a small saucepan over medium heat. Add the onions and salt and cook, stirring occasionally, for 5 minutes.
Add the garlic and Italian seasoning and continue to cook, stirring, for 1 minute. Add the tomatoes and sugar and cook, stirring occasionally, until slightly thickened, 5 to 10 minutes.
Makes about 2 cups.
You can also prepare the dish through step 5, cover and freeze. Add 15 minutes to the baking time when covered with foil.