For the puff pastry, in a food processor combine the flour, salt and 60g/2¼oz of the butter. Add 225ml/8fl oz water and the lemon juice and knead to a smooth dough. Cover with cling film and leave to rest in the fridge.
Take two large pieces of baking parchment and lay them either side of the remaining butter block. Bash the butter block with a rolling pin into a square shape until smooth and pliable. Once the dough has rested for about 15 minutes, roll out to a square large enough so that it will envelope the butter. Seal the butter into the dough and then roll out to a long rectangle and fold the dough over itself into thirds (like folding a letter).
Turn the dough 90 degrees, roll out and fold over again. Cover with cling film and rest in the fridge again. Repeat this process to give 6 turns in total. Rest the dough in the fridge again for about 20 minutes.
While the pastry is resting make the fillings. For the coriander chicken, heat some oil in a frying pan over a medium heat and cook the chicken until browned all over.
Meanwhile, put the onion, peppers, coriander, chillies, ginger, garlic and salt in a blender and blend to a paste.
In another pan, cook the ground spices in a little oil for 1 minute. Add the chicken and cook for a further minute. Add the coriander paste and cook for 5-10 minutes over a medium heat. Add salt as needed and then finish by stirring in the yoghurt and lemon juice to taste.
For the pulled pork, heat a little vegetable oil over a medium heat and brown the pork shoulder steaks on all sides. Add the apple juice and soy sauce and simmer, covered, for 1½-2 hours on a medium heat.
Once the pork is cooked and nearly falling apart, leave to cool in the pan with the juices. Remove to a plate after 15-20 minutes and shred using your hands or two forks.
Grind the fennel seeds in a pestle and mortar. Heat the butter in large wok over a medium heat and add the fennel seeds and rosemary. Cook for 1 minute and then remove the pork from its cooking juices and add it to the wok with the salt. Fry on a medium heat for 2-3 minutes, adding in some of the cooking juices if the meat starts to dry out.
When all the turns are completed, roll the dough out to 5mm thick. Cut out rings using a 5cm/2in crinkled cookie cutter, then, using a 2½cm/1in round cookie cutter, remove the middle. Make 48 of these in total.
Preheat the oven to 200C/180C Fan/Gas 6.
Take the scraps of remaining dough and knead them into a ball. Roll out thinly to 4mm and cut out 48 bases, using the 5cm/2in cutter. Arrange on 2 baking trays lined with baking parchment. Brush the bases with egg wash and prick all over with a fork. Place the rings on top and brush with egg wash again, being careful not to let any egg wash drip down the sides. Bake for 17 minutes, or until cooked through and golden-brown. Remove and set aside to cool.
Assemble the vol-au-vents by placing a little of the chicken or pork filling in each pastry. Top the pork filling with a splash of some of the reserved juices. Serve immediately.