Preheat your oven to 350°F (175°C). Grease a 9-inch tart pan with removable bottom or lightly dust it with flour.

In a medium bowl, combine the all-purpose flour and salt. In a separate bowl, cream together the softened butter and powdered sugar until light and fluffy.

Add the egg yolk to the butter mixture and mix until well combined. Gradually add the flour mixture, mixing until a dough forms. If the dough is too crumbly, add cold water, one tablespoon at a time, until it holds together.

Press the dough evenly into the bottom and up the sides of the prepared tart pan. Prick the bottom with a fork to prevent bubbling. Chill in the refrigerator for 15 minutes.

Bake the crust for 15-20 minutes, or until lightly golden. Remove from the oven and let it cool slightly.

In a large mixing bowl, combine the ricotta cheese, chopped pistachios, granulated sugar, vanilla extract, lemon zest, eggs, and lemon juice. Mix until smooth and well combined.

Pour the filling into the pre-baked tart crust, spreading it evenly with a spatula.

Bake the tart for an additional 25-30 minutes, or until the filling is set and lightly golden on top. A toothpick inserted in the center should come out clean.

Allow the tart to cool in the pan for about 10 minutes before carefully removing the outer ring. Let it cool completely on a wire rack.

Once cooled, garnish with extra chopped pistachios and lemon zest before slicing and serving.