In a large bowl, mix the flour and salt together. Use a cheese grater to quickly grate the butter into the flour. The end of the butter will start to melt in your fingers– that’s ok. Throw it in once you can no longer grate it. Add the frozen shortening.
Using a pastry blender, cut the butter and shortening into the flour until formed into pea-sized chunks (some larger chunks are ok). If you don’t have a pastry blender, use two forks, but a pastry blender is best.
Drizzle cold buttermilk evenly over mixture. Add vegetable oil, distributing evenly. Stir with a large spatula until the dough becomes clumpy.
Pour the dough out onto a clean, lightly floured surface and form dough into a ball with your hands. It should feel slightly tacky, but should not stick to your hands.
Divide the ball in half and flatten each half into a disk. Wrap each disk tightly with plastic wrap and refrigerate for at least 2 hours, or up to 5 days. If you want to freeze your dough, it will last in the freezer up to 2 weeks (just be sure to thaw overnight in the refrigerator if beginning with frozen dough).
Proceed with the pie following your recipe’s directions.
All nutritional values are approximate and provided to the reader as a courtesy. Changing ingredients and/or quantities will alter the estimated nutritional calculations.