Step 1 In a food processor, process the flour, salt and butter for about 5 to 8 seconds, so that some pieces of butter are left. Combine half of the egg yolk (saving the other half for the filling; set aside in the refrigerator) with one-fourth cup cold water and drizzle through the tube of the food processor while pulsing. Pulse until the dough forms a ball and pulls away from the sides.
Step 2 Alternatively, the dough can be mixed by hand. Put the flour and salt in a bowl, cut the butter into pieces and work it into the flour with your fingertips. Make a well in the middle of the flour and butter mixture and add the half egg yolk and one-quarter cup ice water. Stir quickly with a fork to start bringing the dry and wet ingredients together. When the fork can't do any more, use your hands just to bring the dough together. Don't knead or press -- all you have to do is gather up the dry parts as quickly as possible. If your hands get too warm, put them under cold water for a few minutes.
Step 3Wrap the dough in plastic wrap and chill in the refrigerator for at least 30 minutes, or up to 8 hours.
Step 4Heat the oven to 350 degrees. Take the dough out of the refrigerator. Dust your work surface and rolling pin with flour and roll out the dough, lifting and turning it all the time so that it does not stick to the surface. Roll the dough out into a square about one-eighth-inch thick. Roll the dough around the rolling pin and gently lift it into the tart pan, gently pressing the dough into the bottom of the pan and up against the sides. Trim the edges. Chill again for about 30 minutes.
Step 5Line the tart shell with parchment or foil and fill it with pie weights or beans and bake for 15 minutes. Remove the weights and the parchment or foil and prick the crust with a fork. Continue baking an additional 20 to 25 minutes until golden. Cool the tart shell on a rack.