In a large bowl, sift flour with sugar and salt.

Cut in shortening and butter. Pea-sized chunks are fine, but slightly larger chunks will really make a difference.

In a small bowl, whisk together egg yolks and vinegar. Add 2/3 cup of water (more if you live in a dry climate, and less if it is a particularly humid day). You can always add tablespoons of water to the dough later.

Pour the liquids mixture into flour/butter mixture. Stir together and add a little water if necessary. Mixture should be just moist enough for you to form it into a ball. *Note: I like to have just enough moisture so crumbs in the bowl will stick to the dough if you pat them on.

Cover the dough in plastic wrap and place in the refrigerator for 30 MINUTES - this allows the gluten to develop and the dough to get a bit flakier :). (Or so Grandma says.).

Divide into 6 pieces, use what you need, and flatten the rest into 1/4" disks (or 1/8" if you really want to have an easy time thawing the dough). Put them in the freezer and thaw when needed (or just wanted)!