Preheat oven to 400 degrees F. Coat a large shallow roasting pan with nonstick cooking spray. Add eggplant, zucchini, sweet pepper, and onion to prepared pan. Drizzle olive oil; sprinkle herbes de Provence, 1/8 teaspoon salt, and 1/8 teaspoon black pepper. Toss to coat. Roast vegetables 30 minutes, tossing once. Add tomatoes to roasting pan. Roast 15 to 20 minutes more or until vegetables are tender and some surface areas are lightly browned.
Meanwhile, rub toasted bread with cut sides of the garlic clove. Place two small slices or one large slice of the bread on each of four serving plates. Sprinkle balsamic vinegar over vegetables; toss gently to coat. Spoon warm vegetables on bread. If desired, garnish with fresh thyme sprigs. Makes 4 servings.