1. Heat the oven to 190 C/375 F/gas mark 5.
  2. Cut the cucumber into neat thin sticks using a sharp knife and put them in a bowl.
  3. Separate the lettuce leaves and put them into a second bowl.
  4. Put the duck breast in a roasting dish with the skin-side up. Season with salt and pepper and add a splash of olive oil. Put the dish in the oven for 25 minutes, or until the skin is crispy, then remove from the oven.
  5. Transfer the cooked duck to a chopping board and separate the cooked meat into little bits, using 2 forks. Put the meat into a bowl.
  6. Let everyone make their own parcels, wrapping the duck and cucumber in the lettuce leaves, and serve the plum sauce separately on the side to dip into.