Measure the flour into the bowl of a stand mixer and dollop the vegetable shortening and butter into the flour.
Using the flat paddle attachement, beat on low speed until the shortening and butter are incorporated into the flour and the mixture resembles wet sand.
Place the bowl into the fridge or freezer for about 20 minutes. If you live somewhere really cold in winter like I do, I just simply place the bowl outside on the balcony.
Dissolve the salt into the orange juice.
Slowly pour the juice into the flour mixture while beating on low speed. Add just enough juice to bring the mixture together into a ball of dough. If you add too much juice, you might need to add some more flour. If you need more liquid, add some iced water.
Lightly knead the dough into a soft ball, divide into three portions, and wrap each portion in cling film.
Place the dough in the fridge for at least 20 minutes to rest.