Place the chicken, haloumi, lemon juice, olive oil, preserved lemon, garlic, salt and pepper in a bowl and toss to combine. Cover and refrigerate for 30 minutes. Heat the extra oil in a large non-stick frying pan or barbecue hot plate over medium heat. Thread the chicken, haloumi and oregano onto skewers and cook for 2–3 minutes each side or until the chicken is cooked through. Serve with pita bread, baby spinach leaves and lemon wedges. Serves 4.