1
: Preheat oven to 350°F (180°C).
2
: Pastry: Combine flour and salt in large mixing bowl. Cut room temperature shortening into flour with pastry blender or 2 knives until mixture is uniform and shortening resembles large peas. Beat egg, water and vinegar together. Pour all liquid evenly over flour mixture. Stir with fork until all of the mixture is moistened. Divide dough in half and shape each into a ball. Flatten each into a circle about 4” (10 cm). Wrap and chill 15 minutes for easier rolling. If not using the second ball of dough, wrap well in plastic wrap and place in freezer bag and freeze for up to 1 month.
3
: Roll the dough on a lightly floured surface into a circle 1" (2.5 cm) wider than 9” (23 cm) pie plate. Transfer into pie plate. Press into bottom and up sides of plate. Trim overhang and flute edges.
4
: Filling: Combine brown sugar and flour in bowl; stir in evaporated milk, eggs and vanilla, mixing well. Place pie plate on foil lined baking sheet; fill with evaporated milk mixture.
5
: Bake in preheated oven, on bottom rack for 45 to 50 minutes or until set around edges but jiggles slightly in centre. Cool on wire cooling rack. Garnish with whipped cream if desired.