Place the flour and a large pinch of salt onto a work surface. Make a well and add 85 g butter, working it into the flour with your fingertips. Add the vinegar and water and mix until a dough is formed; knead for 5 minutes until smooth and shiny. Roll the dough into a ball and score a cross across the top. Place in a bowl, cover with clingfilm and refrigerate for 1 hour.
Roll out the pastry into a neat square, 30 cm × 30 cm, on a lightly floured surface, keeping the edges straight. Roll out the four corners a little more thinly than the centre of the pastry. Place the chilled square of butter into the centre of the pastry and fold over the four sides to completely enclose. Press the edges together to seal and prevent any butter seeping out when it is rolled. Refrigerate for 30 minutes.
Roll out the pastry into a rectangular shape 20 cm × 60 cm, three times as long as it is wide. Take care that none of the butter seeps through. Fold down the top third of the pastry and then fold the bottom third over it (like folding a letter). Lightly dust the work surface with flour. Give the pastry a quarter turn so that it lies lengthways. Roll out again in exactly the same way. Fold again in thirds and wrap the pastry in clingfilm. Refrigerate the pastry to rest for a further hour.
After 1 hour, roll out the pastry and fold it twice more in exactly the same way as before. Roll in the same direction as before. Wrap in clingfilm and return to the fridge for a further hour.
Roll out the pastry and fold it once more as before. Cut the pastry into three even pieces and wrap each piece in clingfilm. Refrigerate the pastry until ready to use or store in the freezer.
To roll out the puff pastry, work on a lightly floured surface and roll out to a thickness of 5 mm. Place the rolled pastry on a baking sheet and refrigerate for 30 minutes before cutting and baking. Spray a clean baking sheet with water and place the cut pastry onto it. Egg wash the pastry – take care that it does not run down the sides, which will prevent it from rising evenly. Refrigerate for 30 minutes before baking.
Preheat the oven to 200°C. Place the baking tray in the oven and bake the pastry for 7–8 minutes until golden. Reduce the oven temperature to 180°C and continue to cook for a further 2–3 minutes until the centre of the pastry is cooked through.