Add your flour and sugar to a food processor and pulse to combine.
Now add your butter to the processor and pulse again until it comes together.
Add the vanilla and slowly add your water as you turn on the processor. Don't over mix.
Ball up the dough and cover with saran wrap. Chill the dough for at least 20-30 minutes.
After the dough has chilled, sprinkle flour over the clean work surface. Roll out your dough into a large 1/4" thick rectangle.
If you have a stencil, use it. Otherwise, grab a pop-tart or something else rectangle and about the size of your desired pop-tarts and start tracing with a knife around the stencil to create 12 equal rectangles.
After done tracing, cut them with a knife and remove excess dough. If you can't make 12, make as many as you can. Once you've cut out as many as you can, roll out the leftover dough to make more.
Preheat the oven to 400 degrees F. Spray a baking sheet with non-stick spray and line with parchment paper. Place 6 of your dough rectangles on the parchment paper.
Add about 2 Tablespoons of strawberry preserves to the center of each pop-tart and spread around the dough.
Place the remaining 6 rectangles as tops of each of your pop-tarts and press the edges together with a fork to seal the tarts.
Make 6 rows of ventilation holes on each pop-tart top so the filling doesn't escape through the sides.
Bake for 15 minutes or until golden brown. Remove from the oven and cool.
Once they've cooled, make your icing by mixing the powdered sugar and milk together, 1 Tablespoon at a time until you reach your desired consistency.
Spread the icing onto cooled pop-tarts and immediately sprinkle with red sanding sugar.