Cooking the rosti:

1. Grate the potatoes and the parsnip on the coarse side of a grater, squeeze out any excess water.
2. Add the eggs, salt & pepper and mix well.
3. Heat a fry pan and add the oil (you could use the duck fat).
4. When the oil is hot add spoonfuls of the rosti mixture and cook for a couple of minutes on each side. Place into a hot oven and cook for 10 minutes till golden and crisp.

Cooking the duck:

1. Preheat the oven to 190 degrees. 
2. Score the skin of the duck breast 4-5 times and season with salt and pepper. 
3. Heat a pan until you can feel moderate heat coming off it. Place the duck, skin side down into the pan for 5 minutes until golden. Turn the duck breast over and cook for 2 minutes.
4. Place the duck in a roasting tray and cook in the oven for 8 minutes. Remove the duck and let this rest for at least 5 minutes before slicing into it.