In a small bowl, lightly whisk together the egg and water (omit this step for egg-free). Set aside.
On a floured surface (I use tapioca flour), roll pastry out to a 12” square, about 1/4" thick. Cut into 4 squares (or smaller if you want to make bite-sized ones).
Place a folded slice of ham near the corner of each square of dough (leave ½” space to allow for folding). Add some cheese and a bit of the condiment of your choice. Brush the edges of the dough with water, then fold the pastry over to form a triangle. Press the edges together to seal, then crimp with a fork.
If desired, brush with egg wash (to create a golden crust), place onto a parchment lined baking sheet and bake at 400°F for 20 minutes.