In the bowl of a stand mixer fitted with flat beater (paddle) attachment, add the flour, salt and sugar.
Stir dry ingredients briefly to combine.
Add the shortening and pulse carefully to avoid a flour cloud. Beat shortening + flour mixture until crumb stage. It's okay to have some chunks of shortening left.
In a separate bowl, beat the egg and add the water and vinegar.
Add wet mixture to flour/shortening crumb mixture and beat until all wet ingredients are fully incorporated. A loose dough will begin to form.
Dough will be slightly crumbly at this point but pour out onto a pastry mat (or your work surface).
Using the palms of your hands, work the dough until a smooth ball forms. This takes between 3-5 minutes but do not overwork. You just need to work it until a smooth dough comes together (some cracks are okay).
Wrap dough ball in plastic wrap and place in ziploc bag (or in large covered glass bowl) and let chill in refrigerator for at least 2 hours or up to 5 days until needed.