In a medium bowl, whisk together the flour, sugar, and salt.

Scatter the shortening over the flour mixture and use a fork to mash it in. The mixture will resemble coarse sand.

Add the chilled butter over the course flour mixture and use a fork to mash it in.

Sprinkle the ice water over the dough half tablespoon at a time.

Press the dough together. Stop adding ice water once the dough has come together.

Flatten the dough and shape it into a disk. Wrap the dough disk tightly with plastic wrap, and refrigerate it for 20 minutes.

Preheat the oven to 375 degrees F (190 C).

Pinch the edges for a decorative look, if desired.

Prick the pie shell with fork, lightly. Bake for 10 minutes or until light golden. Remove from oven, let cool while you mix the filling ingredients.

Lower the oven heat to 325 degrees F (160 C).

Whisk the egg yolk in a medium bowl and set aside.

In a medium-sized saucepan, add the 1 ½ tablespoons cornstarch, 1/3 cup sugar, 1/8 teaspoon salt, and 1/4 cup water, and whisk to combine. Bring to a boil on medium heat, whisking constantly. Let simmer for a minute or two until the mixture begins to thicken, and then remove from the heat and allow to cool for a couple minutes.

Take a small spoonful of the cornstarch mixture and whisk it into the beaten egg yolk to temper the yolk. Continue to whisk in spoonfuls of the cornstarch mixture until you've used about half of the cornstarch mixture.

Then add the egg yolk mixture back to the pot with the cornstarch. Return to a boil, on medium heat, stirring constantly. Cook 3 to 4 minutes.

Remove from heat and stir in the lemon juice and butter.

Pour the filling into the pre-baked pie shell.

In a regular bowl or stand mixer bowl, add the egg white. Beat with mixer until soft peaks form.

Add sugar and vanilla. Beat until stiff peaks form.

Pour the meringue on top of the pie filling. Spread it out to reach the crust on all sides.

Use a spatula or spoon and make peaks or swirls.

Bake in the 325 degree F (160 C) oven, about 20 minutes, or until the meringue peaks are a light brown and set.