Step 1 In a food processor, blend the flour, salt, sugar and lemon zest until combined, then add the butter and pulse until it's the size of small peas. Add 3 tablespoons of ice water and pulse until the dough just comes together. Form the dough into a disk, wrap it in plastic film, and refrigerate for at least 15 minutes.
Step 2 Once it's chilled, take out the dough and roll it out to about a 12-inch circle. Gently fold the rolled dough into quarters and place it in the pan, with the point in the center, then carefully unfold. Fold the edges over and crimp, trimming any excess dough. Prick the bottom of the shell all over with a fork. Put the tart shell in the freezer for 30 minutes while you heat the oven to 425 degrees and make the filling.
Step 3Place the frozen tart shell in the oven and bake until golden, about 20 to 25 minutes. Let cool on a rack.