Trim the pork from any fats and cut into thick chunks. Marinade with the lemon zest, garlic, parsley, pepper and yogurt, thread the meat on a skewer alternating with the onion wedges. Prepare the couscous according to packet instructions. Drizzle the potato wedges with the oil, season with salt and pepper and bake. Cut the bell pepper, cucumber & tomatoes into neat slices, mix feta cheese, olives, a pinch of oregano and bind with the extra virgin olive oil. Grill the meat kebabs, turning frequently, taking care that the marinade does not burn with the meat until it is cooked through. Grill the pitas on both sides, cut a slice from one end and slit open. Spoon some of the Greek yogurt inside, fill up with some salad and slide the meat inside. Serve warm with the potato wedges.