To make a pie using crushed pineapple in the filling, preheat the oven to 425 degrees Fahrenheit. Place a medium saucepan over a stovetop set to medium heat, and pour in 1 20-ounce can of crushed pineapple and its juice. Stir in 3/4 cup of white sugar, 3 tablespoons of cornstarch and 1 tablespoon of lemon juice.
Continuously stir the mixture until it is thick, and then boil it for an additional minute before removing it from the heat. Allow the mixture to cool slightly as you prepare the pie crust.
To make the pie crust, sift together 1 cup of all-purpose flour with 1 teaspoon of salt. Using a pastry cutter, incorporate 1/2 cup of vegetable shortening until the mixture forms small clumps. Add approximately 1/2 cup of water, adjusting the amount to form a soft dough that is not sticky or crumbly.
Divide the dough in half, and roll out one portion to line the bottom of a pie pan. Trim the edges of the dough in the pan, and then pour in the pineapple filling mixture. Roll out the rest of the dough, and use it to cover the filling by either cutting strips and creating a lattice or by laying the dough over the top and poking ventilation holes into it. Trim off any excess dough around the edges.
Brush the dough with 2 tablespoons of milk, and sprinkle 1 tablespoon of white sugar over the top. Bake the pie in the oven for 35 minutes.