In a mixing bowl, combine the diced apples, lemon juice, ground cinnamon, brown sugar, and flour. Toss the mixture until the apples are evenly coated; set aside to marinate for about 10 minutes.
While the apple mixture is resting, roll out one pie crust on a lightly floured surface. Cut the crust into 4 equal squares.
Spoon about 2 tablespoons of the apple mixture onto the center of each pie crust square, leaving a small border around the edges.
Fold the square over to create a triangle shape, then press the edges together to seal. Use a fork to crimp the edges and ensure they are tightly sealed.
Transfer the hand pies to an air fryer basket lined with parchment paper. Brush the tops of each pie with the beaten egg for a golden finish, and sprinkle with coarse sugar for an extra sweet crunch.
Air fry at 320°F (160°C) for 10-12 minutes or until the tops are golden brown and crispy. Make sure to flip them halfway through for even cooking.
Once done, allow the hand pies to cool for a few minutes before serving.
Notes
Serve warm with vanilla ice cream or caramel sauce for a delightful touch.