Place the pork loin in a greased baking dish and brush with a little barbecue sauce. In a bowl, place the potatoes and season with salt, black pepper, olive oil and oregano and distribute alongside the loin. Cover with aluminum paper and take to preheated oven, 180° for 40 minutes.
Remove the foil, pour the rest of the barbecue sauce and return to the oven. Let it finish cooking and get golden.
Arrange the roasted loin on a platter, the potatoes on the side and place the mold on the stove. Add the wine and water and let it reduce until it becomes a full-bodied sauce.
Spread this sauce over the loin, already sliced, and serve with white rice and green salad.