Step 1

Cut 1 stick unsalted butter and 1/4 cup vegetable shortening into rough 1/2-inch pieces. Transfer to a small bowl and freeze for 15 minutes. Transfer to a food processor with the blade attachment. Add 8 1/2 ounces high-protein all-purpose flour (about 1 1/2 cups) and 3/4 teaspoon of the kosher salt. Process until the mixture resembles coarse breadcrumbs, 30 to 45 seconds. While motor running, slowly pour in 1/4 cup cold buttermilk through the feed tube. Pour in 1 tablespoon ice water in 2 increments. Stop after 30 seconds to check if dough is moist enough and forms a ball when squeezed together. If not, process in more ice water a little at a time.

Step 2

Turn dough out onto a floured work surface and knead until smooth, about 3 minutes. Shape into a ball, wrap in plastic wrap, and refrigerate for at least 1 hour or up to overnight. 30 minutes before you plan to use dough, wrap 10 ounces skirt steak in plastic wrap and freeze for 30 minutes to firm up.

Step 3

Unwrap the steak. Trim and discard any excess fat and sinew if needed. Cut into 1/4-inch cubes. Transfer to a medium bowl.

Step 4

Prepare the following, adding each to the bowl of steak as you complete it: Peel and dice into 1 medium waxy potato and 1/4 small rutabaga; finely dice 1 small yellow onion (3/4 packed cup each). Refrigerate until ready to use.

Step 5

Arrange a rack in the middle of the oven and heat the oven to 375℉. Line a rimmed baking sheet with parchment paper.

Step 6

Dust a work surface with all-purpose flour and line a large plate with plastic wrap. Divide the dough into 4 pieces and place one on the flour. Re-wrap the remaining pieces in the plastic wrap and refrigerate until ready to use. Roll the dough into a round just over 7 1/2-inches wide, between 1/8 and 1/4-inch thick. Invert a 7 1/2-inch round plate on top of the dough. Use a sharp knife to trace around the plate to cut out a round. Transfer the round to the plate and discard the excess pastry.

Step 7

Cover the dough round with a sheet of plastic wrap and place the plate in the refrigerator. Repeat rolling and cutting out 3 more rounds with the remaining dough.

Step 8

Season the steak and vegetables with the remaining 1 3/4 teaspoons kosher salt and 1 3/4 teaspoons black pepper. Use your hands to toss until evenly combined and coated.

Step 9

Beat 1 large egg with 2 teaspoons water in a small bowl. Fill 1 pastry round at a time: Transfer to a floured surface. Place a packed 3/4 cup of the filling in the center. Very lightly brush the edges of the round with the egg wash. Fold the dough in half to form a semi-circle, tucking any pieces of filling that fall out back in. Carefully press down on the center to spread the filling closer to the edges. Firmly press the edges to seal. Transfer to a large plate and refrigerate while you fill the other pastries.

Step 10

Crimp the pasties with a rope effect one at a time: Place on a work surface, arranging it so the straight side is to the left. Starting at the top, fold 1/2-inch over the top corner with your left hand and press and squeeze. Continue to fold down the curved side in 1/2-inch sections, placing your right thumb under each section as you fold (it should look similar to a rope-effect). When you get to the bottom, pinch the end and tuck it underneath the pasty; make sure to create a tight seal. (Alternatively, you can just pinch the edges shut or press the tines of the fork on the rounded edge to seal. Return to the plate and refrigerate as each one is crimped.

Step 11

Transfer the pasties to the baking sheet. Brush all over with egg wash, make sure to brush in all the crevices where there is crimping.

Step 12

Bake for 10 minutes. Check to see if the pasties are sealed properly and not leaking. If they are leaking, remove the baking sheet from the oven and reseal. Continue to bake until deep golden-brown, about 50 minutes more. Let cool for 5 minutes on the baking sheet before serving hot, warm, or at room temperature.