In a large mixing bowl combine butter, sugar, lemon zest and salt. Stir until homogeneous.
Gradually add the flour and mix until a soft dough forms.
Wrap the dough in a cling film and leave it in the fridge for 30 - 60 minutes.
Preheat oven to 180 degrees C (350 degrees F).
Grease and flour the bottom and the sides of a 23-24 cm (about 9 inch) tart pan. Using your fingers press the dough to the bottom and the sides of the pan. Refrigerate for 15 more minutes.
Use a fork to make holes on the bottom of the crust. Bake for 20-25 minutes or until light golden-brown.
Let the crust cool completely before adding the filling.