Take 2 pounds of strawberries and quarter them, setting them aside. Dice half of the remaining strawberries and thinly slice the rest.
In a small bowl, dissolve 1 tablespoon of granulated sugar in the elderflower liqueur. Toss the diced strawberries in this mixture and allow them to macerate at room temperature.
In a medium saucepan, combine the quartered strawberries with the strawberry jam, cornstarch, lemon juice, kosher salt, and the remaining 1/3 cup of granulated sugar. Cook over medium heat, stirring frequently, until the strawberries soften and the mixture thickens into a jam-like consistency, approximately 15 to 20 minutes. Remove from heat and let cool for about 10 minutes. Once slightly cooled, fold in the macerated strawberries.
Pour the prepared filling into the pre-baked pie crust, ensuring an even spread. Transfer the pie to the refrigerator and allow it to set for a minimum of 3 hours.
Arrange the sliced strawberries on top in an overlapping circular pattern for an elegant presentation. Keep refrigerated until ready to serve.
In a mixing bowl, whip the heavy cream with confectioners' sugar, vanilla bean paste, and cream of tartar until medium-stiff peaks form. Serve alongside the chilled strawberry pie.