1.For sage marinade, process sage, thyme, garlic, lemon rind and juice in a food processor until coarsely chopped, add olive oil and season to taste with sea salt and freshly ground black pepper.
2.Wash spatchcocks and pat dry with absorbent paper. Place in a bowl, pour marinade over birds, turning to coat, then cover with plastic wrap and marinate for 3 hours or overnight.
3.Place potatoes in a large saucepan, cover with cold salted water and bring to the boil. Cook for 10 minutes or until half-cooked, drain and combine in a bowl with onion, apple, garlic and olive oil. Season to taste.
4.Preheat oven to 200C. Heat a roasting pan in oven for 15 minutes or until very hot, add potato mixture and cook for 20 minutes, shaking pan occasionally. Drain spatchcocks from marinade, place on top of vegetables and cook for 20 minutes or until starting to turn golden. Pour cider over, scatter with pancetta and sage leaves and cook for another 15 minutes or until golden and vegetables are tender. Serve with pan juices.