Pulse the flour and salt together in the processor, then add the butter and pulse 3-4 times, the butter should be cut up but still be in visible chunks.
Add a squeeze of lemon juice and the iced water, and pulse till the pastry begins to form a ball, then tip out onto the bench and form a ball. Wrap tightly in cling wrap and rest in the fridge for 30 minutes.
Dust the benchtop with flour, then roll the pastry into a long rectangle into a long rectangle three times longer than it is wide, then fold it in three like a business letter. Roll out again to the same length and repeat the fold and roll another 2 times (not rolling out after the last fold).
Wrap in cling wrap and rest in the fridge for another 30 minutes before using it to allow the gluten to relax. When baking, brush with a lightly beaten egg white and bake in an oven preheated to 200 degrees C till puffed and golden brown.