In a large bowl, combine the flour, sugar and salt. Using a fork, stir in oil and butter until dough is crumbly. Gradually add enough water until dough will hold together. Roll out between plastic wrap to an 11-in. circle. Freeze for 10 minutes. Remove top sheet of plastic wrap from pastry; invert onto a 9-in. pie plate coated with cooking spray. Remove remaining plastic wrap. Trim pastry to 1/2 in. beyond edge of pie plate; flute edges. Chill. In a small saucepan, combine the sugar, lemon juice, zest and salt; bring to a boil. Reduce heat; cook and stir until sugar is dissolved. Cool for 10-15 minutes. In a small bowl, beat egg whites and cream cheese until smooth. Beat in eggs. Gradually beat in lemon mixture. Pour into crust. Bake at 350° for 30-35 minutes or until set. Cool on a wire rack for 1 hour. Sprinkle with confectioners' sugar. Refrigerate leftovers.