To make crust: Lightly oil a 9-inch pie plate or coat with cooking spray. Stir together flour, 1 tablespoon sugar and 1/8 teaspoon salt in a medium bowl. Melt butter in a small saucepan over low heat, swirling it in the pan until light brown, about 30 seconds. Pour into a small bowl and let cool. Stir in oil. Slowly stir the butter-oil mixture into the flour with a fork until the mixture is crumbly. Gradually stir in enough ice water so that the dough will hold together. Press the dough into a flattened disk.

Place two 14-inch sheets of plastic wrap overlapping by 2 inches on the work surface. Place the dough in the center and cover with two more overlapping sheets of plastic wrap. Roll the dough with a rolling pin into a circle about 12 inches in diameter. Remove the top sheets and invert the dough over the prepared pie plate. Carefully peel away the remaining plastic wrap. Fold the edges under at the rim and crimp. Chill the dough while you prepare the filling.

To make filling: Place oven rack in lowest position; preheat oven to 350 degrees F.

Grate zest from lemons into a medium saucepan; set aside. Remove the white pith from the lemons with a sharp knife and discard. Working over the saucepan to catch the juice, cut the lemon segments from their surrounding membranes, letting them drop into the saucepan. Squeeze any remaining juice from the membranes into the saucepan. Stir in 2 cups sugar and 1/2 teaspoon salt. Bring to a simmer over medium heat, stirring, until sugar dissolves. Remove from heat.

Whisk together the eggs and egg whites in a medium bowl. Slowly whisk the hot lemon-sugar mixture into the eggs. Pour into the pie shell and bake until the filling is set and light golden on top, 20 to 25 minutes. Let cool on a rack. Before serving, dust with confectioners' sugar.