Slice onions; cut tomatoes into wedges. Cut peppers and eggplant into 1-inch pieces; slice zucchini 1/2-inch thick. In the bottom of a 4-quart casserole place a layer of each vegetable; sprinkle layer with some of the salt, pepper, and parsley. Repeat, making additional layers until all vegetables are used. Mix remaining ingredients; drizzle over top layer. Cover and bake at 350°F for 1 hour; baste the top occasionally with some of liquid in casserole. Remove cover and bake additional 20 to 30 minutes to help reduce the liquid. Serve either hot or cold. Makes 8 to 10 servings.