2) Preheat the oven to 200C/Gas 6. Place the oiled breasts on a hot griddle, skin-side down first, and seal for about 2 minutes on each side.
3) Transfer the duck to a roasting tin and roast in the oven for about 8 minutes, until crisp on the outside but pink in the middle.
4) Remove from the oven and leave to rest for 1 minute before slicing each breast diagonally into six.
To prepare the sauce:
1) Melt half the butter in a large frying pan, add the peppercorns and cook over a medium heat for 1 minute.
2) Add the limoncello with the lemon zest and juice and simmer until reduced by half.
3) Add the chicken stock, season with salt and pepper and continue to cook for about 8 minutes, until the sauce has reduced by half again.
4) Add the remaining butter to the sauce and stir with a wooden spoon until you create a creamy texture.
To assemble and serve:
1) Place the sliced duck in the pan with the sauce and continue to cook for 1 minute allowing the flavour of the limoncello to coat the meat.
2) Sprinkle with fresh mint and serve immediately.