Preheat oven to 400 degrees F. Coat a 9-by-13-inch baking dish (or similar gratin dish) with cooking spray.

Place garlic, basil and thyme on your chopping board; mince well. Spread half the breadcrumbs evenly in the prepared baking dish. Strew onion over the breadcrumbs. Distribute half the diced tomato over the onion, then sprinkle with half the garlic-herb mixture. Sprinkle with vinegar and 1/8 teaspoon salt.

Heat 2 teaspoons oil in a large nonstick skillet over medium-high heat. Add a third of the zucchini; you want it to saute, not stew, so don't crowd it. Saute, turning the pieces once, until golden and not quite tender, 1 to 1 1/2 minutes per side. When the slices are done, use a fork to transfer them to the gratin, overlapping the slices. Cook the remaining zucchini in two batches, each time using 2 teaspoons oil. Strew the remaining tomatoes and garlic-herb mixture over the zucchini. Season with the remaining 1/8 teaspoon salt and a grinding of pepper. Toss the remaining 1 cup breadcrumbs with the remaining 1 tablespoon oil and sprinkle over the gratin.

Bake the gratin until bubbly hot, 20 to 25 minutes. Remove from the oven and immediately sprinkle with Parmesan.

To make fresh breadcrumbs:

Trim crusts from firm sandwich bread. Tear bread into pieces and process in a food processor until coarse crumbs form. One slice of bread makes about 1/3 cup crumbs.