Cut butter into small cubes and place in the fridge to firm up while you get the rest of your ingredients together.
Whisk together the flour, sugar, and salt in a medium sized bowl. Add the shortening and combine with your hands (or a pastry cutter) until coarse crumbs form. After the shortening is fully incorporated, add the cold chunks of butter and work them into the dough until you get pea sized crumbs.
Add in the cold water and combine until dough forms a nice ball but is still slightly sticky.
Take the formed ball of dough and separate into 2 equal sections and shape into slightly flattened disks (you can keep it all together but I find it's easiest to work with only half the dough at a time). Wrap the disks in plastic wrap and chill in the fridge for at least 1 hour. This is important to keep the butter from melting so that the crust will be nice and flaky. The chilled dough is also much easier to roll out.
In a large bowl, smash strawberries with a potato masher until coarsely crushed.
In a large pot over medium heat, add strawberries, sugar, vanilla, lemon juice, and lemon zest. Bring to a simmer and cook for about 20 minutes or until thickened.
Let cool to room temperature and then store in an airtight container in the fridge for up to 2 weeks.
Make sure the filling is completely chilled before assembling the hand pies.
Hand Pie Assembly
Note: I like to work with half the dough at a time. So make half of the hand pies then let those chill in the fridge while you make the other half. Then the second batch can chill in the fridge while the first batch is baking.
Once both the dough and strawberry filling are chilled, preheat the oven to 400°F and line a baking sheet with parchment paper (you may need a second baking sheet).
Lightly flour your work surface and roll out dough to about ¼ inch thick. Use a 3 ¼ inch heart shaped cookie cutter to cut out hearts of dough (re-roll the scraps 1 time). You should end up with about 30 hearts total.
Lightly brush egg wash around the outside edge of each heart. Spoon about 1 tablespoon of strawberry filling into the center of half of the hearts then top with the remaining hearts, egg wash side down. Press the edges together and then seal by crimping the edges with a fork.
Place the hand pies in the fridge to chill 15 minutes before baking.
Remove from the fridge and light brush the tops with egg wash.
Bake at 400°F for 18-22 minutes or until the hand pies are golden brown.
In a small bowl, mix together the powdered sugar and milk, 1 teaspoon at a time, until your desired consistency is reached.
Add in a small amount of the strawberry filling to tint the icing pink.
Both the dough and the filling can be made up to 3 days in advance and stored in the fridge before assembling the hand pies.Store the baked hand pies in an airtight container at room temperature for up to 3 days.