In a large bowl, whisk together the flour, sugar and salt. Work the shortening into the flour mixture with your fingertips until it’s evenly dispersed throughout. Work the butter into the flour mixture with your fingertips, creating flat dime size pieces.
Mix the ice water and vinegar together in a small bowl. Sprinkle over the flour mixture a little at a time, stirring until dough comes together. You may not need all of the liquid depending on your climate.
Turn the dough out onto a lightly floured surface. Fold the dough over onto itself a few times. Do not over work the dough! Form the dough into a disk. Cover with plastic wrap and refrigerate at least one hour or up to overnight.
Lavender Whipped Cream
In a small saucepan, heat the heavy cream and lavender over medium heat, just until bubbles form around the edges. Turn the heat down to low and simmer gently for 1 minute. Strain the lavender cream into a medium bowl. Cover and refrigerate until chilled, about 1 hour.
Whip the lavender cream until thickened. Add the powdered sugar and food coloring, if using. Whip until medium peaks form, being careful not to over beat. Set aside in the refrigerator until ready to use.
Blueberry Filling and Assembly
Line a large baking sheet with parchment paper. On a lightly floured surface, roll the dough into a 12-inch round. Transfer the dough to a baking sheet. Refrigerate for 15 minutes. Meanwhile, preheat the oven to 400ºF (205ºC).
In a large bowl, combine the blueberries, sugar, cornstarch, lemon juice, vanilla extract and salt. Mix until well combined.
Brush a 2-inch border of egg wash on the surface of the pie dough. Spoon the blueberries onto the dough within the border. Fold the dough border over the blueberries, towards the center, pleating the edges about every 2-inches. Brush the edges with egg wash. Sprinkle with coarse sugar.
Bake until the crust is golden brown and the filling is bubbly, about 28-35 minutes. Serve warm or at room temperature with lavender cream.