Preheat the oven to 350 degrees F.
For the lemon curd: Process the sugar and lemon zest together until the zest is finely incorporated. Cream the butter, and beat in the lemon zest sugar. Add the eggs one at a time, followed by the lemon juice and salt and mix until combined.
Make a slurry by whisking together the cream and cornstarch. Pour the lemon mixture into a saucepan and cook over low heat until it begins to thicken, stirring constantly. Add the slurry (you may not need all of it) and continue to stir until the curd is fairly stiff but still spreadable. Remove from the heat and refrigerate until cooled.
For the blueberry compote: Cook the blueberries and sugar together over medium-low heat, stirring occasionally, until the sugar has dissolved and about half the berries have burst, 10 to 15 minutes. Remove and let cool.
For the sourdough pretzel crust: Combine the pretzel crumbs, graham crumbs and butter in a bowl and mix together. Press the mixture into a 9-inch pie pan to create the crust, and then bake until lightly golden brown, 20 to 25 minutes. Let cool.
Spread the curd into the cooled pie shell and refrigerate for at least 1 hour. Cut into 8 wedges. Put each on a plate and garnish with a generous dollop of compote, a scoop of gelato, a sprig of fresh mint and a slice of lemon.
Freeze fresh berries at the peak of the season so that you have them on hand to use all year long. Any type of berry or fruit can be substituted for blueberries.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.