Sift the dry ingredients excluding the sugar into a bowl and rub in the butter or fat to form 'breadcrumbs'
Mix in the sugar then add some of the water to form a soft but not sticky dough
On a floured surface knead until smooth and crack free
Split the dough into 2, wrap in clingfilm and refrigerate for half an hour before use
Roll out the dough between 2 sheets of floured parchment paper as gf pastry can be quite tricky to move without breaking but patches very easily. If making a pie, slip a plate under the bottom parchment, peel off the top one, put the pie dish on top and flip it over, then press the dough into the tin
Can be frozen. Just follow your recipe for cooking times. To blind bake use gas 6 / 200C / 400°F for 20 - 25 minutes
For a whole grain crust, replace the rice flours and cornstarch amounts with 75g millet flour, 75g sorghum flour and 60g gf oat flour
This is enough for 2 x 9" pie crusts / shells
