Step 1

Preheat oven to 200°C.

Step 2

Combine walnuts, breadcrumbs, butter and 2 tablespoons parsley in a bowl and season, then divide between the butterflied pork. Fold to enclose the filling, then secure each piece with kitchen string in 4 places.

Step 3

Heat the oil in a large, ovenproof frypan over medium-high heat. Cook pork, turning, for 3-4 minutes until browned. Transfer to oven and roast for 8-10 minutes until cooked through. Rest, loosely covered with foil, for 5 minutes.

Step 4

Meanwhile, combine celeriac, horseradish, yoghurt, juice and remaining 1 tablespoon parsley in a bowl and season.

Step 5

Slice pork and serve with the celeriac remoulade and extra walnuts.