In a mixing bowl, combine the flour and salt. Mix well.
Add the cold, cubed butter into the flour mixture. Using a pastry cutter or your fingers, work the butter into the flour until it resembles coarse crumbs with pea-sized pieces of butter remaining.
In a small bowl, mix the cold water with vinegar (or lemon juice).
Gradually add the cold water mixture to the flour and butter mixture, stirring gently with a fork until the dough comes together. Do not overmix.
Turn the dough onto a lightly floured surface and shape it into a rectangle. Wrap it in plastic wrap and refrigerate for at least 30 minutes.
After chilling, take the dough out of the fridge and place it on a floured surface. Roll it into a large rectangle (about ¼ inch thick).
Fold the dough into thirds (like a letter). Rotate it 90 degrees and roll out again into a rectangle. Repeat this rolling and folding process three more times.
Once finished, wrap the dough in plastic wrap and chill for an extra 30 minutes before using. Alternatively, you can freeze it for later use.