Cut the butter into about ¾" pieces. Keep in the refrigerator until needed. The butter needs to be very cold.

Place the dry ingredients in the bowl of a mixer fitted with the paddle attachment. Mix briefly to combine.

Add the chunks of cold butter. Mix on low to break the butter up but keep it in large pieces.

Add the sour cream and mix to bring it together. Add the water and mix to form large crumbs.

Pour the crumbs onto a work surface. Push the crumbs together to form a block of dough. Knead 3 or 4 times to smooth it out, keeping the butter in large pieces.

Press a rolling pin into the dough about 3 or 4 times several inches apart from top to bottom. These "hills and valleys" will help roll out the dough more evenly,

Sprinkle the surface lightly with flour. Roll the dough to about a 16" x 8" rectangle. If the pastry begins to soften, chill it until firm.

Brush off any flour and fold the top and bottom to the center of the pastry, leaving a ½" channel.

Fold the top over the bottom, creating a book like pastry. Turn the pastry 90° with the fold to the right.

Lightly sprinkle the surface with flour and repeat the rolling and folding. Wrap in plastic wrap and chill until cold through out, overnight or up to 3 days.

With the pastry parallel to the edge of the surface divide the pastry in half (approximately 300 grams). Refrigerate ½ half of the pastry.

Roll ½ of the pastry into a 12 ½" x 12 ½" square. With a 6" round guide (a saucer or cake round is fine) cut 4 rounds out of the pastry. Refrigerate. Repeat with the second half of the pastry. Chilling it also.

Place one round in front of you and fill with ¼ cup of filling of your choice. Wet the edges of the pastry with water and bring the top over the filling matching the edges. Seal with a fork. Refrigerate. Repeat for the other 4 rounds.

When ready to bake, preheat the oven to 375°F. Place 4 cold pastries on a parchment lined baking sheet and brush them with the beaten egg. Cut two vents in each pastry.

It is best to bake one sheet at a time for about 20 to 25 minutes until medium brown. Refrigerate the second tray until baking.

Serve lukewarm or room temperature. These reheat in the microwave for 20 seconds.

Store at room temperature uncovered for a day or two. Do not cover or they will become soggy.

Roll one half of the dough into a 12 ½" x 14 ½" rectangle. Trim to 12" x 14". cut the 12" side into 12" x 6" pieces. Cross cut to 7" x 6". You will have 4 pieces of pastry that are 7"x 6". Refrigerate.

Place ¼ cup filling of your choice slightly below the middle of the pastry. Wet the edges and bring the top of the pastry down over the filling making sure there is about ½" without any filling round the 4 sides. Using the tines of a fork, seal the crust all the way around. Refrigerate.

When ready to bake preheat the oven to 375°F. Place 4 pastries on two parchment lined baking sheets. Brush with the beaten egg and cut 2 vents in each pastry. Bake for 20 to 25 minutes until medium brown. It is best to bake one tray at a time. Refrigerate the second tray until bakiog.

Cool to luke warm . Serve lukewarm or room temperature. These reheat in the microwave for 20 seconds.