Place flour and salt on a cool surface. Make a well in the center. Pour in the lemon juice and water. Work flour into the water with your fingertips to make a soft dough. If it seems dry, add water.
Gather dough into a ball. Cover tightly and refrigerate 20 minutes (dough will not be smooth at this point).
Lightly flour the butter and place between 2 sheets of waxed paper. Beat with a rolling pin until pliable. Press into a 5 inch square.
On a lightly floured surface, roll out the dough from the center to make a 12 inch square. Make dough thicker in center than on the sides. Place the butter in the middle and fold the dough around it envelope fashion.
Roll out the dough into an 18 x 8 inch rectangle. Fold a third of the dough over the center. Brush off any excess flour. Fold remaining third over the 2 layers. Give the dough a quarter turn. Do this roll/fold/turn 3 more times.
Wrap and refrigerate 40 minutes.
Preheat oven to 400.
Repeat 4 roll/fold/turn process twice refrigerating between steps.
Roll to 1/8th inch and cut to shape pastry as desired.