Combine the blueberries, cornstarch, granulated sugar, and lemon juice together in a medium saucepan or skillet over low-medium heat. While occasionally stirring, bring to a simmer. Allow to simmer for 2 minutes. Remove from heat and allow to cool uncovered at room temperature for 30 minutes.
Measure flour and salt into bowl. Cut in shortening thoroughly. Sprinkle in water, 1 tablespoon at a time, mixing until all flour is moistened and dough almost cleans side of the bowl. (1 or 2 teaspoons water can be added if needed).
Gather dough into a ball and turn the dough about a quarter turn after every few rolls. At any sign of sticking, sprinkle some flour underneath then keep rolling.
Roll out until it's about 12 inches in diameter and about 1/8th - 1/4th inch thick. Using your cookie cutter, cut into circles. Re-roll any scraps and cut into circles.
Refrigerate cut circles for at least 15 minutes before filling the hand pies.
Meanwhile, preheat oven to 375°F (191°C). Line one large baking sheet with parchment paper or silicone baking mats.