Prepare pastry: In large bowl, combine flour and salt. Cut vegetable shortening and butter into flour mixture until coarsely blended. Slowly add water, mixing, until dough binds. Form dough into two balls, one slightly larger than the other; wrap and refrigerate.
Make apple filling: Cook apple slices in a large pot over medium-low heat, stirring occasionally, until barely tender—about 10 minutes. Watch so they don't burn! Drain apple slices completely. Transfer to large bowl and add sugar, cinnamon, nutmeg, and vanilla; stir to blend. Set aside.
Prepare Pecan Crumb Topping: In medium-sized bowl, combine flour, brown sugar and salt. Cut butter into flour mixture until mixture resembles cornmeal. Add pecans and mix.
Preheat oven to 400 degrees. Roll out out both pieces of dough. Place the smaller round in bottom of dish. Carefully fill pie dish with apple filling. (It will be quite full!) Roll our larger piece of dough to a 12-inch round and cover top of pie. Trim and pinch together edges of bottom and top crusts.
Brush top crust lightly with water. Top with crumb topping and carefully press into crust. Make several slits in top pie crust.
Put a tray beneath the pie to catch any overflow during baking. Bake 45-50 minutes or until crust is golden brown. Cool at least 25 minutes, sift confectioners’ sugar over top, and serve.