Cube the vegan butter and place it back in the fridge for at least 15 minutes. Fill a bowl with ice water and set aside. Chill your food processor bowl and blade or mixing bowl if your kitchen is warm.
Add flour, sugar, and salt to the bowl of a food processor and pulse 3-4 times to combine. If making by hand, whisk together in a large mixing bowl.
Scatter cold cubed vegan butter over the flour mixture. Pulse in short bursts 8-10 times until it looks like coarse crumbs with pea sized pieces of butter still visible. If using a pastry blender, cut in until you reach the same texture.
Stir apple cider vinegar into the ice water. With food processor running, drizzle in ice water one tablespoon at a time. Stop when dough starts to clump when pinched, about 6-8 tablespoons. For hand method, sprinkle water over flour mixture and toss with a fork.
Turn shaggy dough onto a lightly floured surface. Gently gather together and divide into two equal portions. Shape each into a flat disc about 1 inch thick.
Wrap each disc tightly in plastic wrap. Refrigerate for at least 1 hour, or up to 2 days, before rolling out.
Let chilled dough sit at room temperature for 5-10 minutes if too firm. On a lightly floured surface, roll one disc from the center outward into a circle about 12 inches wide. Rotate the dough a quarter turn every few rolls. Use a bench scraper if it sticks.
Roll the dough loosely around your rolling pin, then unroll over your 9 inch pie dish. Press into the bottom and sides without stretching. Trim overhang to 1 inch, fold under, and crimp the edges with your fingers or a fork. For a double crust pie, repeat with the second disc for the top layer.
For a filled pie, follow your filling recipe's baking time and temperature. For a blind baked crust, prick the bottom with a fork, line with parchment and pie weights, and bake at 375°F for 15 minutes. Remove weights and parchment, then bake another 5-8 minutes until lightly golden.