In the bowl of a food processor, pulse together flour, salt and sugar. Add the shortening and butter and pulse until mixture resembles coarse sand.
Add 4 tablespoons of water and pulse until dough has almost come together. If dough is dry, add another 1-2 tablespoons of water. Turn dough onto a clean working surface and push dough together into a cohesive mass.
Divide dough into two pieces, one slightly larger than the other. Flatten the two pieces and wrap separately in plastic wrap. Chill in the fridge for at least 1 hour, up to 2 days.
Remove dough from fridge and let stand at room temperature until pliable. Roll the large piece into a rectangle about 15 x 11-inches, about 1/4-inch thick.
Using a knife or pastry wheel, cut the rectangle into strips about 3/4-inch wide. Place strips in the fridge to chill, about 15-30 minutes. Meanwhile, roll out the smaller dough on a lightly floured surface to about an 11-inch circle, about 1/4-inch thick. Place pie plate upside down over the rolled dough to ensure it is the right size.
Transfer rolled dough to 9-inch pie plate. Firmly press dough into the bottom and sides of the pan. Trim excess dough, leaving a 1/2-inch overhang. Cover with plastic wrap and place in the fridge to chill for 15 minutes.