Wash the duck and remove any excess fat from around the cavity. Pat the duck dry with a paper towel. Place on top of a wire rack and place the rack in the kitchen sink. Pour boiling water over the duck, flip the duck over and pour water on the other side, this helps to tighten the skin. Transfer the rack onto a baking tray or roasting tin lined with aluminium foil and refrigerate for 2 hours, uncovered to dry the skin.
While the duck is drying, make the glaze. Place the honey, brown sugar, soy sauce, Chinese five spice and water into a small saucepan over medium-high heat and simmer for 1 minute, to dissolve the sugar. Remove from the heat, stir in the Chinese cooking wine and set aside.
Preheat oven to 200°C. Place the spring onions, star anise, cinnamon stick, garlic cloves, ginger and the peel of one mandarin inside the duck and secure the cavity with a metal skewer.
Place the duck breast side down back on the wire rack and brush with the glaze. Roast for 30 minutes, brushing frequently with the glaze.
Turn the duck over and brush with the glaze. Roast for a further 30-40 minutes, brushing frequently with the glaze until cooked. Remove from the oven and allow to rest for 15 minutes before slicing.
Peel the remaining mandarins, slice all three thickly crossways. Place the mandarin slices and duck slices on a serving platter and scatter with coriander. Spoon over any pan juices.