For mincemeat, peel, core and grate apple, squeezing out excess juices. Chop raisins, almonds and dried apple and toss with grated fresh apple. Stir in currants, candied peel, sugar, orange or lemon juice, orange zest and spices until evenly coated. Stir in melted butter and sherry. Cover bowl and let sit in the fridge for at least 24 hours.
For pastry, combine flour, sugar and salt. Cut in butter and shortening until a rough, crumbly texture. Whisk egg with lemon juice and ¼ cup of cold water. Add to flour mixture and blend just until dough comes together, adding more water if needed. Shape dough into 2 discs, wrap and chill for at least 2 hours.
Preheat oven to 375 degrees F.
On a lightly floured surface roll out 1 disc of dough to just less than ¼ -inch thick and line a 9-inch pie plate. Trim edges of pastry. Spread mincemeat filling to shell. Roll out remaining disc of dough and cut out desired shapes (such as stars or circles) and arrange, overlapping, over mincemeat filling.
Brush pie with egg wash and sprinkle with Turbinado sugar. Bake for 15 minutes, then reduce heat to 350 degrees F. and bake 30 minutes more until pastry is richly browned and the filling bubbles. Allow to cool for at least 30 minutes before slicing.