Preheat oven to 400 degrees F.
Mix sausage, apple, onion and seasoning together in a bowl or food processor. If using a food processor, pulse just until blended to keep the texture of the filling.
On a floured surface, roll out pastry to 1/8" to 1/4" thickness. Using round cutters, cut out circles. (The size of the cutter will determine the amount of filling and the number of hand pies you'll get.) I made 10 small, 4" pies and a half dozen larger, 6" pies.
Use about 1 1/2 Tablespoons filling for the small pies and about 3 Tablespoons for the large pies.
Moisten the edges of the pies with water and fold over, using the back of a fork to seal the pies.
Place on a cookie sheet lined with parchment paper or a silicon baking mat.
Brush pies with egg wash.
Bake at 400 degrees F. for 15 minutes. Lower the oven temperature to 350 degrees F. and continue baking an additional 15 to 20 minutes, until golden brown.