Prepare the fish by making 3 slits on each side of the fish. Season with salt and pepper then lightly oil both sides of the fish.
In a small bowl, mix together the tomatoes, garlic, capers, and olive oil. Season to taste.
Lay out a piece of greaseproof paper large enough to wrap and fold over the whole fish. Place the fish on top of the paper then lay the lemon slices, and tomato mixture on top of the fish. Fold the greaseproof paper over to cover the fish, crimp all the edges until the fish is secure.
Bake in the oven for 20 minutes.
Take out of the oven, and garnish with fresh parsley and basil leaves on top.