In a large bowl, whisk together the flour, sugar and salt. Work the shortening into the flour mixture with your fingertips until evenly dispersed. Work the butter into the flour mixture with your fingertips, creating flat dime size pieces.

Mix the ice water and vinegar together in a glass measuring cup. Sprinkle over the flour mixture a little at a time, stirring until the dough comes together. You may not need all of the liquid depending on your climate.

Turn the dough out onto a lightly floured surface. Fold the dough over onto itself a few times. Do not over work the dough. Divide the dough into 6 equal portions, about 2 ounces (57g) each. Form the portions into disks, wrap them individually with plastic wrap and refrigerate for at least 1 hour or up to overnight.

Preheat the oven to 400ºF (200ºC). Line a large baking sheet with parchment paper.

On a lightly floured surface, roll the dough portions to 1/8-inch thickness. Cut out six rounds, about 4 1/2-5-inches each. Place the rounds on the prepared baking sheet. Spread about 1/2 teaspoon of mustard on each round. Top each one with ham (or veggies) and cheese. Brush the perimeter edges with egg wash. Fold the rounds over and press the edges to seal. Crimp the edges with a fork. Brush the pies with egg wash and sprinkle with Everything Bagel Seasoning. Cut a 1/2-inch ventilation slit into the top of each pie. Bake until golden brown, about 22-25 minutes. Transfer the pies to a cooling rack. Serve warm.