Most lemon tart recipes feature butter in both the crust and the filling, but here we use extra-virgin olive oil instead. It makes the crust a snap: Just mix the flour, sugar, and salt with the oil and a little water until a soft dough forms; crumble it into the tart pan; press it into the sides and bottom; and bake it right away—no rolling or chilling required.
Using olive oil in the filling doesn’t compromise its firmness or sliceability, because the filling gets plenty of structure from the protein in the eggs. Olive oil does, however, allow lemons’ acidity to come to the fore in a way that butter doesn’t. That means we can use a bit less juice and still enjoy plenty of bright lemon flavor.
