1. Preheat oven to 350 F. Lightly grease 8-by-8-by-2-inch baking dish. With stiff brush, scrub zucchini well. Cut crosswise into 1/4-inch slices.
2. In medium bowl, combine flour with 1/2 teaspoon salt, 1/2teaspoon oregano, and 1/8 teaspoon pepper. Toss zucchini slices in seasoned flour, to coat them well.
3. Slowly heat oil in large, heavy skillet. Saute6 zucchini until golden brown - about 4 minutes on each side. Drain.
4. Cover bottom of baking dish with zucchini. Top with tomato slices. Combine sour cream, rest of salt, oregano, and pepper, and spread evenly over tomato slices. Then sprinkle with grated cheese.
5. Bake 30 to 35 minutes, or until cheese is melted and zucchini is tender.