To prepare crust, lightly spoon flour into a dry measuring cup; level with a knife. Combine 1/4 cup flour, water, and juice in a small bowl, stirring with a whisk until well blended to form a slurry. Combine 3/4 cup flour, powdered sugar, and 1/4 teaspoon salt in a medium bowl; cut in shortening with a pastry blender or 2 knives until mixture resembles coarse meal. Add slurry; toss with a fork until flour mixture is moist.
Gently press mixture into a 4-inch circle on 2 sheets of heavy-duty plastic wrap that overlap; cover with additional overlapping plastic wrap. Roll dough, still covered, into a 12-inch circle, and freeze 10 minutes. Remove 2 sheets of plastic wrap; let stand 1 minute or until pliable. Fit dough, plastic-wrap side up, into a 9-inch pie plate coated with cooking spray. Remove remaining plastic wrap. Press dough against bottom and up sides of pan. Fold edges under; flute. Freeze 10 minutes.
To prepare filling, combine granulated sugar, cornmeal, and 1/4 teaspoon salt in a medium bowl; stir well. Combine milk and remaining ingredients in a large bowl, stirring well with a whisk. Add cornmeal mixture, stirring with a whisk until blended. Pour into crust. Bake at 325° 50 minutes or until just set. Cool completely on a wire rack.