Preheat oven (electric cooker: 180 °C/circulating air: 160 °C/gas: see manufacturer). Wash duck breasts, dab dry, season with salt and pepper. Fry on the skin side in a pan without fat for about 10 minutes. Turn and continue to roast in the oven for 6-8 minutes. Wrap in foil, let rest for about 5 minutes.
In the meantime clean, wash and cut the leek into pieces. Cut bacon into strips. Fry in a pan without fat until crispy. Take out and drain on kitchen paper. Steam leek in bacon fat for 3-4 minutes. Clean and wash the chicory and cut it into leaves. Wash the watercress and parsley, shake dry and pluck.
Mix vinegar, mustard, salt and pepper. Add the oil. Wash the apples, if necessary cut out the core. Slice or cut the apples into thin slices. Cut the meat open, mix everything and serve.