Make the crust:
In a bowl or stand mixer, combine the flour, sugar, salt, and orange zest.
Cut the butter into the flour mixture until it forms pea-sized crumbs.
Add the egg yolks and sour cream, and mix just until the dough comes together into a ball.

Place the dough on plastic wrap on your work surface and flatten it into a disk. Refrigerate for 30 minutes.
Have a 13-inch (33 cm) round baking pan, 3/4-inch (2 cm) high, ready.
Lightly flour your work surface. Place the dough on it and roll it out to a 13 1/2-inch (34.5 cm) circle.

Roll the dough onto your rolling pin and transfer it to the pan, covering the bottom and sides.
Gently press the dough into the edges of the pan.
You can create a decorative edge if you like.
Place the pan with the dough in the refrigerator for 20 minutes.

Preheat the oven to 400°F (204°C).
Prick the bottom of the crust all over with a fork to prevent it from puffing up while baking.
Bake the crust for about 20 minutes, or until the edges start to turn golden.

Remove from the oven and, if the crust has puffed up, gently press it down with a spatula. If it resists, carefully poke a small hole with the tip of a knife to release the air.
Let the pan cool on a wire rack.

Make the pastry cream:
In a small saucepan, heat the milk until just about to boil.
In a mixing bowl, whisk the egg yolks with the sugar and cornstarch.
Slowly pour the hot milk into the egg mixture, whisking constantly.

Return the mixture to the saucepan and continue to cook and whisk until the cream thickens. Remove from heat, then whisk in the butter and vanilla. Transfer the cream to a bowl to cool. Once slightly cooled, refrigerate for a couple of hours until fully chilled.

Assemble the tart:
Spread the pastry cream over the crust, leaving a small border and making sure it doesn’t overflow.
Decorate with the fruit, starting from the edge and working toward the center.

Using a pastry brush, lightly glaze the fruit with the jam. If you’re not serving the tart right away, refrigerate it immediately since it contains cream made with eggs. This helps prevent bacterial contamination.