Preheat the oven to 375° F.
Toss the zucchini, onion, tomato and olives with 1 tablespoon of the oil in a baking dish. Brush another tablespoon of oil over the fish and place on the vegetables. Place in the oven and bake for 25-30 minutes until cooked through.
Whisk together the garlic, lemon juice, mustard and remaining oil to make a dressing.
Divide the cooked vegetables among plates and top each with a piece of fish.
Drizzle the fish with the dressing and scatter with chopped parsley.Servings: 4