Preheat oven to 200°C (390ºF). Rinse the turkey breast and pat dry with absorbent paper. Combine the butter with the oregano and salt and pepper. Spoon between the skin and breast meat.
Place the potato in a baking dish and place a greased wire rack on top of them. Place the turkey, skin-side up, on the rack and sprinkle with salt and pepper. Cover loosely with greased aluminium foil and bake for 35 minutes. Uncover and bake for a further 20 minutes or until golden brown and cooked through. Serves 6–8.