Place the flour salt and salt in the bowl of a food processor, pulse briefly to combine. Add the butter and water. Pulse until just combined. At this point you should be able to pinch the dough together with your fingers. If it's too crumbly add the tiniest bits of ice water until the dough just sticks together. Transfer the dough to a large, clean work area. Divide dough into two portions and press into flat disks. Wrap each disk in plastic wrap. Refrigerate for at least one hour or up to two days.
In a medium saucepan combine the strawberries, sugar, lemon juice, vanilla and salt. Heat over medium high heat, stirring constantly with a spatula or wooden spoon until the strawberries start to sizzle. Reduce heat to medium low and continue to cook and mix for 10-15 minutes, until the berries release their juices and become saucy. Transfer the strawberries to a heat proof container and let cool to room temperature. Once cool, place in a food processor and pulse until smooth. Store in the refrigerator until ready to use.
Preheat oven to 375°F. Line two sheet trays with parchment paper or spray with nonstick cooking spray and set aside.
Remove the dough one disk at a time from the fridge. Remove the plastic wrap and let the dough sit out a few minutes on a lightly floured work surface. Roll the dough to 1/8 inch thick. With a sharp knife or pizza cutter, trim the dough to 4 X 2 1/2 inch rectangles. Save any scraps and continue to roll until you don't have enough dough left to continue. Do the same process with the second disk. You should end up with 22 rectangles.
Make the egg wash: whisk together the egg with the milk and salt.
Spread one tablespoon of the strawberry filling onto the center of eleven rectangles. Brush some egg wash on the edges of the dough. Place the other eleven pieces of dough over the ones with the filling. Crimp the edges with a fork to seal the tarts. Using a paring knife, cut three small slits or "X's" in the top of each pop tart. This will ensure that the pop tarts don't explode while baking. Place the filled pop tarts onto the baking sheets with and inch in between each tart.
Brush the egg wash on the tops of each pop tart. Bake for 25-30 minutes or until golden brown. Remove from the oven and let cool.
While the pop tarts are cooling make the frosting. Whisk together the powdered sugar with milk and vanilla. Add a few drops of food coloring if desired. Drizzle the frosting over the pop tarts and add sprinkles while the frosting is still runny. Let the frosting set for a few minutes. Serve at room temperature.
Store at room temperature in an airtight container. Enjoy within 3 days.
Serving Size 1 pop tart