Sieve flour and salt into a clean, dry mixing bowl, and add lemon juice and a quarter of the diced butter. Rub together lightly with the tips of your fingers until the mixture resembles fine breadcrumbs. Then mix with just enough iced water to make a rather stiff dough. Turn this out on to a floured board and work it well with the hands until it no longer sticks to the fingers and is perfectly smooth. Then roll it rather thinly into a square or round shape. The remaining butter to be used should be as nearly as possible of the same consistency as the dough, so work it with your hands into a neat thin cake and place it in the centre of the dough. Fold dough up rather loosely, and flatten the folds with a rolling pin. Then roll the pastry out into a long narrow strip, being careful not to allow the butter to break through.
Fold dough exactly in three; press down the folds and lay the pastry aside in a cool place for at least 15 minutes. This is called giving the pastry one “turn”; seven of these operations are usually required for puff pastry.
The next time the pastry is rolled, place it with the joins at your right-hand side and the open ends towards you. Give it two turns this time, and again put it in the refrigerator for at least 15 minutes.
Repeat this until the pastry has had seven rolls in all, one roll or turn the first time, and after that two each time with an interval between.
The object of cooling the pastry between rolls is to keep the butter and flour in the distinct and separate layers (in which the rolling and folding has arranged them), and on which the lightness of your pastry depends.
When rolling, keep the pressure of your hands on the rolling pin as even as possible.
After you have given the pastry its last roll, put it in the refrigerator for ½ hour before using it, then roll to the required thickness. This pastry will keep for several days in the refrigerator if wrapped in a piece of waxed paper or in a damp cloth.