Preheat oven 375. LIghtly oil 3 qt baking dish. Spread 1/2 potatoes on bottom of dish. Sprinkle with garlic, parsley, onion, tomato, peppers, salt & pepper. Top with remaining potatoes, pour 1 cup water over, bake 1 hour. Meanwhile, season fish w/salt & pepper, let stand 10 minutes. Raise oven temp to 425*. Remove and discard foil. Add fish on the bed of potatoes. Lay lemon slices atop. drizzle with oil. Add bay leaf, sprinkle with thyme, bake 13 minutes. Add sherry, bake additonal 2 minutes. Remove bay leaf and serve.