This is their recipe, with a few small tweaks. Visit their site!
Julie's Mennonite Gluten Free Pastry
1. Blend well together the flours, guar gum, salt and sugar. (flours for gluten-free baking must be well-blended)
2. Cut in butter (*for this step,remove butter from freezer, and GRATE directly into flour mixture,tossing to coat with flour.. Work quickly so butter does not get too gummed up!)
3. Beat egg , add vinegar and ice-water.
4. Stir into flour mixture forming a ball. (Add a *little* more water if too dry)
5. Knead until you have a smooth soft ball.(* It will seem quite crumbly, but if you squeeze a handful and it holds together, it is ready. Lay out two sheets of plastic wrap. Place 1/2 dough on each. Press dough into a ball using the plastic wrap, until smooth and combined. Flatten each ball slightly into a fat "pancake". Try not to handle the dough too much, as you don't want to melt the shreds of butter- that is what makes the dough nice a flakey! )
6. Refrigerate dough for 1 hour or more to chill.
7. Roll out between plastic wrap dusted minimally with sweet rice flour.Peel off top layer of wax paper , flip over onto pie plate and then carefully peel off the other layer of wax paper and fit pastry into pie shell fluting edges -- for single crust pie or for double add filling and then top with top crust .
NOTE: I must also add that I could not remember whether or not to grease the pie plate, so I did. I highly recommend that you do the same! The bottom did not stick, held together beautifully, and had a really nice crunch. Enjoy!