Place the remaining butter between two sheets of clingfilm and beat it out firmly with a rolling pin to form a smooth 15 cm (6 inch) square, then set aside.
Make a well in the center of the flour, add the lemon juice and iced water.
Mix with a round-bladed knife to form a fairly soft, but not t sticky dough.
Place the dough on a lightly floured marble slab or work surface, and without kneading, roll out the dough to about 25 cm (10 inch) square.
Place the square of butter in the center of the dough, so that it looks like a diamond shape.
Bring each corner of the dough to the center of the butter, to enclose tit completely, then turn the pastry 45 degrees to square it up.
Roll out the pastry to about 45.5 cm (18 inches) long.
Take the bottom third of the pastry up and over the center third.
bring the top third of the pastry down over the bottom third, trapping in as much air as you can between each layer, as you do so.
Press the edges firmly with a rolling pin to seal.
Wrap the pastry in clingfilm, put it on a plate and chill for 30 minutes.
Remove the clingfilm.
Place the pastry on a lightly floured surface so that the short joined ends are at the top and the bottom.
Roll out the pastry again to about 45.5cm (18 inches) long.
Fold into three once again and seal.
Brush off excess flour, then wrap and chill for 30 minutes.
Repeat this rolling out, and folding process six more times with a 30 minute rest between each one.
After the last folding and the 30 miute rest, the pastry is ready to be used.
It may be wrapped in clean clingfilm, then in aluminium foil and refrigerated for up to 3 days before using, or frozen for up to 3 months.
