Put the flour, sea salt and sugar, if using, in a food processor and pulse to combine.
Sprinkle the cold butter over the flour in the food processor. Pulse until the mixture looks crumbly with larger, pea-sized chunks of butter (those chunks of butter equal a flaky crust!). Drizzle the apple cider vinegar over top.
Turn the machine on and immediately start drizzling cold water through the feed tube. Stop the machine once the mixture starts to come together and looks shaggy. Give the dough a pinch—if it sticks together, it’s ready to go. If not, turn the machine on again and drizzle in a bit more water. You might not need all of the water—you’re looking for a shaggy dough, not a cohesive ball.
Transfer the dough to a lightly floured surface and shape it into a ball. Divide the dough into 2 equal pieces and form each into a flat disk. Wrap the disks in plastic wrap and refrigerate them for at least 30 minutes or for up to 2 days. Do Ahead: The wrapped disks can be placed in zip-top freezer bags and frozen for up to 3 months. Thaw in the refrigerator overnight before using.
If the dough has been in the fridge for several hours, let it sit at room temperature until slightly softened, about 10-20 minutes. Roll it out on a lightly floured piece of parchment paper. If the dough immediately starts to crack once you start rolling, it’s too cold—give it a few more minutes to warm up. If the edges crack as you roll (which they probably will, so no fear!) simply patch them as needed.