Pre-heat oven to 450 F. Line a 9-inch pie pan with pastry, rolled 1/8-inch thick, allowing pastry to extend 1 inch beyond edge. Fold edge back to form standing rim; flute or crimp with fingers (That is a fun part for kids to help with!). Fill pie shell with thinly sliced apples. Cover with mixture of sugar, salt, and cinnamon; sprinkle with melted butter. Bake in hot oven for 15 minutes; then decrease oven temperature to 375 F, and back for 25 minutes longer. Quickly top with coconut and continue baking 5 or 6 minutes longer, or until coconut is delicately browned. Serve cold. You can also warm it up and put vanilla (or coconut!) ice cream on top!