Place dry ingredients in a food processor and pulse to mix (include optional sugar or herbs here). Add cubed butter and shortening and pulse until it looks like coarse crumbs, about 10 pulses. While the processor is running, slowly add ice water into feeding tube so it drips in. 

When dough merges into a ball turn off processor. Place dough on plastic wrap, removing blade carefully and scraping all the dough into the ball. Wrap and refrigerate at least two hours, or preferably overnight.

Place one half of the dough on a large piece of plastic wrap covered in flour. Cover top with more flour and another layer of plastic wrap. Press down with rolling pin in one direction and then the other. Roll from center out into a circle making sure dough is not sticking. Add more flour if necessary. 

Form dough into pie pan. Proceed with your pie recipe.

Repeat steps 3 and 4 for second pie crust.

Image credit - Tim Horel