Pre-heat the oven to 200° C.
Rub the pork fillet with the sunflower oil then season generously. Heat a large frying pan over a high heat until hot. Sear the pork fillet until golden brown in colour all over. Transfer to a roasting tray and finish cooking in the oven for 40-45 minutes depending on desired cooking degree.
Meanwhile, melt the butter in a large saucepan set over a medium heat. Add the apples and cook, stirring occasionally, until golden brown in colour at the sides. Season and set to one side.
Remove the pork and allow it to rest, covered loosely with aluminium foil, for 5-10 minutes. Re-heat the apples at this point. Slice the pork fillet into slices and arrange on a serving plate. Spoon the apples around the perimeter. Sprinkle the pork with the fennel seeds and garnish with a sprig of chervil leaves before serving.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home.