Combine the hoisin sauce, soy sauce, sherry, sugar, ginger, garlic, Chinese five spice, cinnamon and star anise in a shallow bowl. Add the pork and turn to coat. Place in the fridge to marinate for 1 hour. Pre heat oven to 280 C. Transfer pork mix to a shallow roasting pan and arrange in a single layer. Cover with foil and cook, turning occasionally for 2 hours, or until tender. Remove foil and cook for 30 minutes or until sauce thickens and pork it tender. Cook the bok choy in a steamer over a saucepan of simmering water for 1 minute or until vegetables are bright green. Use tongs to quickly transfer to a bowl of ice water to refresh. Serve immediately with rice and pork.