Puff Pastry:

In the bowl of a food processor, add 2 cups of all-purpose flour, 1 tbsp of granulated sugar, 1/2 tsp of salt, and 1/2 tsp of baking powder. Pulse a couple of times to mix the dry ingredients.

Add in 2 sticks (16 tbsp) of cold European-style unsalted butter that's been cut into pieces. Pulse this till the pieces of butter are the size of small peas.

3.) Add in 1/2 cup of cold sour cream and pulse till the mixture just comes together.

Transfer this mixture into a large mixing bowl. Knead the mixture into the bottom of the bowl with your hands until it forms a cohesive dough. Form the dough into a flat disc, wrap it in plastic wrap, and refrigerate for 1 to 2 hrs., until it reaches 50 to 60 F (10 to 16 C).

When it reaches 50 to 60 F (10 to 15 C), roll it into a 8" x 10" rectangle. If you find the dough sticking to the counter or the rolling pin, sprinkle a little bit of flour on the dough surfaces and spread it out evenly with your hands, as needed. Try not to add too much flour, as this will prevent the dough from sticking to itself when folding. I like to constantly invert the dough while rolling out to prevent it from sticking to the counter. Use a bench scraper to create straight edges and 90-degree corners as much as possible. Brush off any excess flour from the surfaces. Folding the 8" ends, fold it into thirds, like you're folding a business letter, making sure to brush off any excess flour from the surfaces before each fold, so the dough sticks to itself. Pat it down and straighten the edges as needed. Transfer this dough to a parchment paper-lined baking sheet, cover with plastic wrap, and let the dough rest in the fridge for 1 hour, or till the butter reaches 50 to 60 F (10 to 16 C).

When the butter has cooled to 50 to 60 F (10 to 16 C), rolling the longer side to 10", roll the dough into another 8" x 10" rectangle. Use the same technique as above to prevent the dough from sticking to the counter. Again, use a bench scraper to create straight edges and 90-degree corners as much as possible. Folding the 8" ends, fold it into thirds, like you're folding a business letter. Pat it down and straighten the edges as needed.

After the 2nd letter fold, transfer this dough to a parchment paper-lined baking sheet, cover with plastic wrap, and let the dough rest in the fridge for a minimum of 2 hours, preferably overnight.

Peach Mango Filling:

In a small saucepan, add in 1 1/2 cups of chopped mangoes (fresh or frozen), 1 1/2 cups of chopped peaches (fresh or frozen), 3 tbsp cornstarch, 3/4 cup granulated sugar, 1/2 tsp salt, 1 1/2 tbsp lemon juice, and 1/4 tsp ground cinnamon. Mix these together till well combined.

Heat over medium-high heat till the liquid at the bottom starts to simmer. When it starts to simmer, turn down the heat to medium and continue cooking, stirring constantly, till the mixture starts to thicken, about 5 minutes.

Remove from the heat and add in 1/2 tsp of vanilla extract and stir it in. Take a small sheet pan and line it with parchment paper. Divide the filling evenly into 10 approximately equal amounts, shaping them into long tubes that are about 4" long. Let these cool completely to room temperature.

Assembling and Baking the Hand Pies:

Beat 1 large egg in a small bowl to make an egg wash and set it aside. Prepare 2 large sheet pans (the exact size doesn't matter, but we use 13" x 18" pans) by lining them with parchment paper.

Place the cold dough on a clean flat surface. It should be around 40 F (32 C). Roll it into a thin rectangle that is 10" by 25". It should be about 1/8" thick. If you find the dough sticking to the counter or the rolling pin, sprinkle a little bit of flour on the dough surfaces and spread it out evenly with your hands, as needed. Try not to add too much flour, as this will prevent the dough from sticking to itself when folding. I like to constantly invert the dough while rolling out to prevent it from sticking to the counter. Then cut the 10" side equally into two, resulting in 2 long strips that are 5" x 25". Then cut the 25" long side equally into five, resulting in 10 small squares that are approximately 5" x 5" each.

Transfer the squares of dough onto the prepared parchment paper-lined sheet pans, 5 squares per pan. Let the squares rest in the fridge for an hour to let the dough cool to below 60 F (16 C).

Once the dough squares reach below 60 F (16 C), taking one tray out of the fridge at a time so that the dough remains as cool as possible, preventing the pockets of butter from melting, add the pre-divided peach mango filling onto the middle of each square.

Bring two ends of the dough together lengthwise to cover the filling, then press all sides together to seal the filling inside the dough. Crimp further with the tines of a fork to tighten the seal along the 3 edges with a seam. Do this for all 10 pies, 5 pies per baking sheet.

Carefully brush the top of each pie with the prepared egg wash. Try not to get egg wash on the sheet pan, or it will burn. Use a knife to cut 3 vents on each pie, which will prevent the pie from bursting during baking.

Take 2 tbsp of white sparkling sugar, and sprinkle one generous pinch on top of each pie. Place the two trays of prepared pies in the fridge while the oven preheats, to keep the dough cold and prevent the pockets of butter from melting.

Place 2 racks on the upper and lower third positions of your oven, and preheat your oven to 400 F (205 C). Bake in the preheated oven at 400 F (205 C) for 20 to 23 minutes, or until they are golden brown. Remove them from the oven, and let them cool on a metal rack for 20 minutes before serving. Freeze for long-term storage. Enjoy!