Cut 6 pieces of foil, each measuring about 10-inches square. Brush the foil squares lightly with oil and set aside until needed.
With a sharp knife, slice each chicken breast at intervals across the top. (only slice slightly) Slice the mozzarella cheese and place between the cuts in the chicken.
Divide the zucchini and tomatoes between the pieces of foil and sprinkle with pepper to taste. Tear or roughly chop the basil or oregano and scatter over the vegetables in each packet.
Place the chicken on top of each pile of vegetables then wrap in the foil to enclose the chicken and vegetables, tucking in the ends. Place on a baking sheet and bake in a preheated oven, 400F for about 30 minutes. To serve, unwrap each foil packet and serve with rice or pasta