In a large bowl, whisk together flour, salt and sugar. Add the chilled shortening and using a pastry cutter, or two forks, cut the shortening into the flour mixture until it resembles coarse sand.
Next, add the cold butter cubes and use the pastry blender, or two forks, to cut the butter into the mixture until it resembles coarse crumbs, with bits about the size of small peas. If there are a few larger bits, no worries, that bite of pie will be extra good.
Sprinkle the ice-cold water, one tablespoon at a time, into the bowl. With a rubber spatula, use a folding motion to mix. Once large clumps start to form, do not add any more water. I typically use about 6 tablespoons.
With your hands, form the dough into a large ball and transfer to a lightly floured work surface. Divide the dough into two equally-sized disks. Wrap tightly in plastic wrap and refrigerate for at least 1 hour, or up to 2 days, before rolling.
Sprinkle flour on the counter and roll out one dough. If the dough was kept in the refrigerator longer than 1 hour, wait 5 to 10 minutes until dough is malleable enough to roll. Roll the dough about 2 inches past the rim of a 9-inch pie pan.
Lay the crust in the pie pan and press down lightly on the bottom and up the sides of the pan. Roll out the other crust and set on a separate plate. Place both crusts in the refrigerator while you make the pie filling.
Triple Berry Pie Filling
Place berries, sugar and lemon juice in a large saucepan over medium heat. Simmer, until warm and juicy, about 5 to 10 minutes, stirring occasionally.
Gently stir 4 tablespoons cornstarch into berries and allow to simmer until thickened, about 5 minutes. If the mixture is still runny, add another tablespoon of cornstarch and simmer for 1 minute loner. You want the berry mixture to be thick.
Remove from heat and stir in the butter. Let filling cool for 15 minutes (it will thicken a bit).
Remove pie plate from the refrigerator and pour warm berry mixture into unbaked pie shell. Use second pie crust to make a lattice top (step by step instructions above). Alternatively, layer a full crust on top and add slits to let steam escape. Crimp the crust edges.
Brush a thin layer of beaten egg white over the top of the pie and sprinkle lightly with sugar.
Bake at 400° F for 40 to 45 minutes. Check pie after about 25 minutes and place a piece of aluminum foil over the pie to prevent the crust from burning.
Remove pie to a wire cooling rack and allow to cool. Once cooled completely, cut into slices and serve or cover it and refrigerate it overnight to serve the next day.
Storing berry pie: Once cooled, store pie in the refrigerator for up to 3 days. This will help the pie keep its structure.Freezing berry pie: Once cooled, cover the entire pie and pie plate with aluminum foil. Place pie in a freezer safe bag and freeze the pie for up to 3 months. Uncover and defrost in the refrigerator before serving.Suggested tools:
Kitchen scale to accurately weigh ingredients (more accurate than measuring).