In a food processor, combine flour and salt. Next, add chunks of cold butter. Turn on processor and pulse until the butter has blended into the flour. 

Remove lid and add egg yolk and blend. 

Finally, add ice cold water, one tbsp at a time until dough starts to form. Remove dough from food processor, press into a disk, and cover in plastic wrap. Refrigerate for 2 hours or overnight. 

To prepare filling, prepare strawberries. If using fresh strawberries, slice and add sugar, and allow to set. The sugar should draw out the natural juices.

If using frozen sliced strawberries, place in colander and allow to thaw for up to two hours. I do so by placing them in a colander, over a bowl. After strawberries have thawed, transfer to a bowl and then add sugar. 

To the strawberry and sugar mixture, add pinch of salt, corn starch and vanilla. Stir mixture and set aside. 

Remove pastry dough from refrigerator. Place on a large sheet of parchment paper, which has been sprinkled with gluten free flour. Using a rolling pin, roll into a rough 10-12 inch circle. It doesn't have to be an exact circle, and the edges can be shaggy. 

Leaving approximately a 2" gap from the edge, place filing in the center of the pastry dough. Fold the edges of the rolled dough up over the filling, naturally creating creases as you fold. 

In a small dish, combine egg and water, whisk with a fork, and coat the pastry edges with egg wash. If desired, sprinkle with sugar. 

Bake at 400 for 25-30 min.

Best served warm, with ice cream or whipped cream on top.