Preheat electric oven to 400°F. Whisk the egg and milk together. For each turnover, place puff pastry on the work surface with a corner facing you so it looks like a diamond. Place 3 apple wedges on the upper half of the diamond, forming a triangle. Sprinkle each apple wedge with 1 tablespoon of sugar. Dampen edges lightly with egg mixture. Fold the bottom corner of the puff pastry over to the opposite corner, forming a triangle; seal edges. With a knife or scissors, cut a vent in the top of the pastry. Brush turnovers lightly with egg mixture; sprinkle generously with coarse sugar. Bake for 24 to 25 minutes, or until puff pastry is golden brown. Makes 12 apple turnovers.