Preheat oven to 375F/190C degrees. Lightly grease a baking sheet, or line with parchment paper or a silicon baking mat.
FOR THE PIE DOUGH:
Sift together the flour, baking powder, and salt into large bowl. Cut shortening and butter into flour mixture using hands or pastry cutter until there are small pieces of the shortening and butter throughout.
Make a well in the center of flour mixture and add the egg. Gently mix the egg into the flour using your hands, gradually adding water as needed, until dough comes together and is still soft but not sticky. Form into a large ball, cover with plastic wrap and set aside.
FOR THE FILLING:
Place olive oil in a large skillet over medium heat and saute onions, peas, curry powder, and cumin for 3-4 minutes. Remove from the heat.
Stir the turkey, mashed potatoes, and cilantro into the curry mixture Add salt and pepper to taste. Set aside the mixture.
Make the egg wash by lightly beating the egg with the 1 tablespoon water. Set aside.
TO ASSEMBLE THE PIES:
Uncover dough and divide into 6 balls of equal size. Take one ball, keeping the rest covered to prevent from drying out, and roll out into a ¼" thick, 5" circle. Fill the circle with about ½ cup turkey mixture and fold over top to make a half circle.
Lightly press down on the top to press out any air inside and fold/crimp the edges to seal together. Place pie on baking sheet and repeat process with remaining dough balls.
Lightly brush the tops of pies with the egg wash mixture. Bake for 10-15 minutes or until golden brown.
The hand pies can be frozen before baking. Place pies on lined baking sheet and place in freezer until frozen, then store in freezer proof bags. Bake at 375F degrees from frozen for 20-25 minutes.