Prepare the Crust Mix: In a large mixing bowl, whisk together all-purpose flour, almond flour, sugar, and salt until combined. Cut in chilled butter until the mixture resembles coarse crumbs.

Form the Dough: In a medium bowl, whisk together egg, vanilla bean paste, lemon zest, and cardamom. Gradually add to flour blend, stirring gently until a soft dough forms. Wrap in plastic wrap and refrigerate for at least 30 minutes.

Bake the Crust: Preheat oven to 375°F. Roll out the dough into a 9-inch tart pan. Prick the bottom and line with parchment paper. Bake for 20 minutes, then remove weights and bake for another 5 minutes.

Create the Frangipane Layer: Lower oven temperature to 350°F. In a bowl, beat together softened butter and sugar until fluffy. Add another egg and vanilla bean paste; fold in almond flour and spread over the crust.

Prepare the Fruit Filling: In a separate bowl, combine rhubarb, strawberries, sugar, honey, tapioca starch, lemon juice and zest, and ground ginger. Let sit for 10 minutes.

Assemble and Bake the Tart: Pour fruit filling over the frangipane. Brush edges with beaten egg wash, sprinkle with coarse sugar, and bake at 350°F for 40-45 minutes.

Cool and Serve: Let the tart cool on a wire rack for 2 hours. Serve with whipped cream or ice cream.