This is a deliciously easy, Italian-style, baked fish dish. Sea bass is served on a bed of roasted potatoes with garlic, rosemary, cherry tomatoes and olives. If it starts to become dry while cooking, add a few drops of white wine.
Place the sliced potatoes in a colander and wash under cold running water. Drain well and pat dry with kitchen roll. Transfer potatoes into a large baking dish, spreading them out evenly. Drizzle 2 tablespoons olive oil on top of potatoes; season with salt and add rosemary. Toss well and roast potatoes in preheated oven for 45 minutes, shaking the baking dish half way through cooking to make sure the potatoes are not sticking to the bottom.
Mix 3 tablespoons of olive oil, parsley, garlic, salt and pepper together in a small bowl.
Remove the baking dish from the oven; gently push the potatoes to both sides of the baking dish and place the fish in the middle. Spread the oil mixture on the top of each fish and into the cavity. Place the garlic into the cavity so it doesn't burn. Scatter halved cherry tomatoes and olives on top.
Return the dish to the oven and bake for 20 minutes, or until fish flakes easily with a fork.