3 cups plus 3 tbsp all-purpose flour
1 cup shortening
1 cup sugar
4 tablespoons unsalted butter, melted
zest of 1 lemon
1/4 cup lemon juice
2 large eggs, yolks and whites separated
1 cup milk
In a food processor or with a pastry blender mix 3 cups flour and shortening until mixture is the consistency of cornmeal, about 10 pulses. Add 1/3 to 1/2 cup ice water to form dough. Divide dough in half. On a floured surface roll one half into a 12-inch circle and line a 9-inch pie pan; chill in refrigerator. Freeze remaining dough for later use.
Heat oven to 450 degrees F. with rack in the lower third. Stir together 3 tablespoons flour, sugar, butter, zest, lemon juice, egg yolks, and milk. In a separate bowl beat egg whites to stiff peaks and fold into lemon mixture.
Pour into crust and bake 10 minutes. Reduce oven to 350 degrees F. and bake until a knife inserted into center comes out clean, about 30 minutes. If top of pie gets too dark, tent with foil.