Cook lasagna noodles in boiling salted water until al dente, then drain.
3
In a large skillet, heat olive oil over medium heat. Sauté zucchini, eggplant, and bell pepper until tender, about 5-7 minutes.
4
In a bowl, mix ricotta cheese with oregano, salt, and pepper.
5
Spread a thin layer of marinara sauce in a baking dish. Place 3 noodles over the sauce.
6
Layer half of the sautéed vegetables, spread half of the ricotta mixture, add a layer of mozzarella, then repeat with remaining noodles, vegetables, ricotta, and mozzarella.
7
Top with remaining marinara sauce and mozzarella cheese.
8
Cover with aluminum foil and bake for 40 minutes. Remove foil and bake for an additional 10 minutes until cheese is bubbly and golden.