Mix together flour, salt, and one tablespoon sugar. Cut in butter. Add water, 1 tablespoon at a time until dough forms.
On a floured surface, roll out dough into ¼ inch thick sheet. Cut dough into 12-16 equal sized rectangles, and transfer to a baking sheet.
In a small pot, heat berries with 1 tablespoon of sugar and corn starch until berries have softened and reduced. Use a spoon to mash them so there aren't any big chunks.
Spoon about 1 tablespoon of compote onto a dough square, place another square on top of the compote, and use a fork to seal them together (you may want to wet the edges of the dough a little bit to help stick). Continue until you run out of fruit or dough.
Use a fork to poke a couple holes in each pop tart and bake for 20-25 minutes.
Let cool for a couple of minutes and then enjoy your flashback to the 90s.
Recipe by Things I Made Today at https://www.thingsimadetoday.com/2013/03/10/berry-pop-tarts/