Prick the duck’s skin really well with a fork (this helps release the fat from the skin as it roasts). Mix the soy, 5-spice and honey in a large bowl, add the duck and coat well. Cover and place in the fridge until ready to roast.
For the gravy, tip the stock into a pan, add the hoisin sauce and ginger and boil for a few minutes to make a smooth gravy. Add the sesame oil and set aside.
To serve, preheat the oven to fan 180C/conventional 200C/gas 6. Pour 1 litre of water in the base of a roasting tin and place a rack over the top – this stops fat from the duck dripping on to the tin, then burning and filling the kitchen with smoke. Lift duck from marinade and arrange on rack, skin side up. Reserve remaining marinade for the rice dish. Roast for 20 minutes for medium and 30 minutes for well done. Slice each breast in half. Spoon some rice on to each plate; top with halved duck breasts. Add any meat juices from the duck to the hoisin gravy and pour a spoonful or two over the duck. Serve the remaining rice and gravy separately.