On a large baking sheet, combine eggplant, zucchini, onion and bell pepper. In a separate small bowl, mix oil, lemon juice, garlic, basil, oregano and salt. Drizzle over vegetables, tossing to coat.
Roast for 20 minutes or until vegetables are tender. Halfway through cooking time, remove from oven and stir in diced tomatoes with liquid. Transfer back to oven and roast for 10 more minutes.
Meanwhile, place baguette slices on a large baking sheet. Spray with nonstick butter spray or brush with butter, and toast in oven until golden, 5-6 minutes. Remove from oven and top each slice with a pinch of mozzarella. Transfer back to oven for 2-3 minutes to melt cheese.
Top each toast slice with heaping 1 tablespoon vegetable mixture and a sprinkle of parsley. Serve warm or at room temperature.