In a large bowl, add the flour, salt, and 1 tablespoon of sugar. Mix in butter with a fork until it is in small crumbs. Add 2 tablespoons of cold water (or a little more) to bring the dough together. Cover the dough and refrigerate for 20 minutes.
Place the dough onto a lightly floured working surface. Slightly knead and roll the dough with a rolling pin to form an 8 x 20 inch (20x50cm) rectangle.
Preheat oven to 400 F / 200˚C.
Roll out the dough to a thickness of about ¼ inch (5 mm). Cut circles the size of your tart molds. Press the dough into the molds all the way up to the edges. Place the tart molds on a baking sheet.
Then, reduce the temperature to 350 F / 180˚C, and bake for another 12 minutes, until the custard is set. Leave the oven door ajar for 5 more minutes before removing the egg tarts from the oven.