In a food processor, combine flour, powdered sugar, almond flour, salt, and orange zest. Pulse in chilled butter until the mixture resembles coarse crumbs. Add the egg yolk and cold water, and mix until a dough forms. Wrap in plastic and chill for at least 15 minutes.

On a lightly floured surface, roll out the dough into a 12-inch circle. Transfer it to a greased tart pan and press into the edges. Chill in the refrigerator for 15 minutes. Preheat the oven to 375°F (190°C) and bake with pie weights for 12-15 minutes. Remove weights and bake for an additional 10-12 minutes until golden. Let cool completely.

In a medium saucepan, gently heat the orange juice over low heat. Whisk together egg yolks, superfine sugar, and cornstarch in a bowl. Gradually add the warm juice to temper the eggs, then pour back into the saucepan. Cook on low for 5-7 minutes, stirring until thickened.

Remove from heat and stir in the gelatin and unsalted butter until melted. Pour the curd into the prepared crust. Smooth the top and refrigerate for at least 3 hours.

Whip the heavy cream with powdered sugar in a chilled bowl until stiff peaks form. Garnish the tart with whipped cream, fresh orange segments, crushed pistachios, and mint.