Method

1. Add a little olive oil to a pan and sweat off the onion until softened, then transfer to a plate and allow to cool
2. In a large bowl, season the pork generously with salt and pepper, then mix in 1 tbsp of the wholegrain mustard, the chopped sage, onion and the breadcrumbs. Mix in the cream until all the ingredients are combined
3. Heat a little more oil in the pan and fry off a small piece of the pork mixture until cooked through – check the seasoning is to your taste, and adjust the main mixture if needed
4. Lay a large piece of clingfilm (approx. 40cm x 30cm) out on a flat work surface, then spread out the pork mixture to a rectangle, slightly smaller than the clingfilm (approx. 30cm x 20cm)
5. Mix the diced apple with the remaining 1 tbsp of mustard and season, then place in a line down the centre of the pork mix. Use the clingfilm to fold the meat tightly around the apple, so it is encased in the centre of the meat. Twist up the ends of the clingfilm to make a neat and compact sausage shape, then chill for 30 minutes to firm up
6. Preheat the oven to 160°C/gas mark 3
7. Unroll the sheet of puff pastry and brush with the egg yolk glaze. Remove the sausage from the fridge and carefully unwrap the clingfilm. Place along one edge of the pastry, and roll up tightly to enclose the roll (there should be about a 2cm overlap on the join of the pastry). Trim any excess pastry and press the seam together to seal
8. Transfer the sausage roll onto a heavy baking sheet. Score the top lightly or decorate with shapes made from any leftover pastry if liked. Brush all over with the egg to glaze and bake for 40–45 minutes, or until golden brown. Serve with fresh salad and apple slices to garnish