From Art of Gluten-Free Baking
http://artofglutenfreebaking.com
Pie Crust, Gluten-Free (makes a double crust for a 9 inch pie)
Ingredients
2 1/3 cups (335 g) Jeanne’s Gluten-Free All-Purpose Flour Mix
1 tablespoon granulated sugar
1/4 teaspoon salt
1 cup (8 oz; 230 g; 2 sticks) unsalted butter, cold and cut into pieces.
(if you want to use a substitute for the butter like lard or shortening or butter replacer, use volume measuring to make the substitution–weight will not work well for the substitution. If you use a butter replacer, you will probably need less water than with the other fat options because of the amount of water in most butter replacers. Also, butter replacers are often very salty. If the one you’re using is salty, omit the salt in the recipe. Also, do not use a liquid fat like ghee.)
1 tablespoon vinegar (or just more water if you don't want to use vinegar)
1-7 tablespoons cold water
extra tapioca flour for rolling out
1 egg beaten with 1 tablespoon of water for an egg wash (optional)
extra granulated sugar for sprinkling top (optional)
Temperature is important, so work quickly. Place flour, sugar, and salt into a large bowl. Mix together with a spoon until combined. Add butter pieces to the dry ingredients mixture. With fingers, start rubbing together the butter and the dry ingredients. This will take a bit of time but you want to work as quickly as you can to make sure the butter doesn’t get warm and start to melt into the dough. Do this until the resulting mixture looks like wet sand mixed with different-sized pebbles. I like to do this by hand to get a feel for the dough, although you may also do this initial cutting of the fat into the dry ingredients with a pastry blender or by pulsing the ingredients in a food processor.
Add the vinegar and rub into the mixture. Add water a tablespoon at a time, rubbing into the mixture. You want to add just enough to create a dough that holds together well, but isn’t wet. The less water=the more flaky crust.
Divide the dough into two fairly equal pieces, shape into disks, and wrap each disk separately in plastic wrap. Refrigerate the disks for 20-ish minutes (or until the disks are cool and nicely firm but not rock hard) If you store the dough longer and they become rock hard, you will need to leave them out on the counter to warm up to optimal rolling temperature (but no warmer) before rolling.
BIG NOTE: You can roll out the dough between 2 pieces of plastic wrap if you prefer.
NOTE: if your kitchen isn’t too hot, you can roll out your first crust right away. Just put the other piece in the fridge to chill while you roll out the first piece. My kitchen in Seattle rarely gets too hot, so I always roll the first piece right away. This is always the easiest dough to roll–it is probably at the right temperature. Note that the optimal pie crust dough temperature is 65 to 67 degrees F/18 degrees C to 19 degrees C.
Prepare your rolling surface. Sprinkle tapioca flour over your rolling surface. Also sprinkle flour over your rolling pin. When the disks are chilled to 65 degrees F to 67 degrees F/18 degrees C to 19 degrees C, remove the first disk of dough from the fridge and place on your prepared rolling surface and sprinkle top of dough with tapioca flour. A key to successfully rolling out gluten-free pie dough is to go slow. And use a light touch. If your dough starts cracking, slow down and don’t press so hard with your rolling pin. With your rolling pin, carefully and patiently roll out the dough into a 12″ circle (it should be at least 3″ larger than the top of your pie pan). If the dough sticks to the rolling pin, add more tapioca flour.
NOTE: the dough should be cool but not too cold. It should roll fairly easily and should not break while you’re rolling it. If it does break a little bit, don’t worry–breaks are easily fixed by smoothing the dough over the breaks. If it seems too cold and you’re really having to work hard to roll it and it’s breaking a lot, step back and let it warm up a little bit before you continue. Alternately, if the dough is floppy and seems to be “sweating,” it is too warm and should be refrigerated for a while longer to cool it down.
In the next step, you are going to roll the dough around the rolling pin in order to transport it to the pie pan. In order to do this, sprinkle tapioca flour over the entire surface of the pie crust dough. Now, put the rolling pin on top of one side of the dough. Wrap the dough around the roller until you’ve gotten all of the dough onto the pin. If it’s at the right temperature, the dough should roll easily around the pin without any breaking.
NOTE: again, if the dough breaks a lot while you’re rolling it around the pin, it’s a bit too cold. Step away and let the dough warm up a bit before proceeding
Lift the pin with the dough rolled around it and put on the top of your pie pan
Unwrap the dough from your rolling pin onto the pie pan so the pan is covered evenly. Now carefully press your dough into place. Proceed slowly, starting with the middle bottom of the pie pan and working out to bottom corners and then up the sides.
When you get to the rim, press the dough onto the rim. Finally, press down and carefully tear off any leftover dough (set these scraps aside–you will use them later)
Place your pie pan with the bottom crust dough into the refrigerator while you roll out the top dough.
Preheat your oven to the temperature required for your chosen pie filling.
Roll out the top dough the same way you rolled out the bottom dough.
Remove pie pan w/dough from refrigerator. Place filling inside it and dot with cold butter pieces.
Roll top crust dough onto your rolling pin just as you did with the bottom crust dough. Transfer and unroll over the top of your pie filling.
Carefully press top and bottom crust dough together at the rim to form a seal. You can create a decorative edge by pinching the dough together with your thumb and forefinger of one hand and the forefinger of the other hand. Or, you can carefully press down along the rim with the tines of a fork. Be sure you’ve created a good seal–any unsealed portion will leak filling all over your oven floor during the baking process.
Now make slashes in the top crust dough to create air vents for steam to escape during the baking process. I usually do two levels of them–the top row alternating with the middle row–to make it decorative.
If you are so inclined, roll out some of the leftover scrap dough and cut out cute designs to put on the top of pie. For example, for an apple pie, I cut out an apple with a leaf.
Also, if you want a little bit of a glaze on top of your pie, I recommend using some beaten egg to brush on the top and then sprinkle with granulated sugar. It will create the effect of the top photo of this post.
Now your pie is ready for the oven! Your baking time and temperature will depend on your filling.