Preheat oven to 375°F
Combine tomato sauce, onion, basil, salt, pepper and oregano in small mixing bowl.
Set aside.
In medium bowl, combine ricotta, mozzarella and parsley
Set aside
Slice zucchini lengthwise into strips (making it look like strips of lasagna noodles)
Arrange zucchini in 8x8 baking pan.
Layer 4 to 6 of the strips in the bottom of baking dish
Reserve 6 strips for second layer
Spread ricotta mixture over zucchini
Layer with sliced tomatoes
Spread half of tomato sauce mixture over tomatoes; top with zucchini slices
Pour remaining sauce over zucchini and sprinkle with Parmesan
Bake for 15 minutes.
Drain any excess juice from the lasagna.
Bake for another 15 minutes or until zucchini is tender.