How to Make It
To prepare crust, lightly spoon flour into a dry measuring cup; level with a knife. Combine flour and 1/4 teaspoon salt in a bowl; cut in butter and shortening with a pastry blender or 2 knives until mixture resembles coarse meal. Add vinegar and ice water, 1 tablespoon at a time; toss with a fork until moist. Gently press the mixture into a 4-inch circle on heavy-duty plastic wrap; cover dough with additional plastic wrap. Roll dough, still covered, into a 12-inch circle; chill 10 minutes.
Preheat oven to 425°.
Remove 1 sheet of plastic wrap; let dough stand 1 minute or until pliable. Fit the dough, plastic-wrap side up, into a 10-inch round removable-bottom tart pan. Remove plastic wrap. Press dough against bottom and sides of pan. Fold edges under. Line dough with a piece of foil; arrange pie weights on foil. Bake at 425° for 10 minutes or until edge is lightly browned. Remove pie weights and foil; cool on a wire rack.
To prepare filling, heat a large nonstick skillet over medium heat until hot. Add bacon, and cook 4 minutes. Remove bacon from pan, reserving 2 teaspoons drippings in pan; set bacon aside. Add leek to drippings in pan; cover and cook for 20 minutes, stirring occasionally. Sprinkle with 1/4 teaspoon salt and 1/8 teaspoon pepper. Remove from heat. Arrange leek mixture and bacon in prepared crust.
Combine egg substitute, milk, 1/4 teaspoon salt, and 1/8 teaspoon pepper; stir well with a whisk. Pour the milk mixture into crust. Bake at 425° for 25 minutes or until a knife inserted in the center comes out clean; let stand 10 minutes.
Note: You can use a commercial piecrust (such as Pillsbury) in place of the pastry crust. If you substitute an refrigerated piecrust, follow the package instructions for prebaking. It will add 15 calories and 4 grams of fat to the nutrition figures for each serving.