Perfect Lemon Meringue Pie

Crust

1. Follow the recipe for my foolproof all butter flaky pie crust recipe to make 1 pie crust. The linked recipe is for 2 crusts, so you can either halve it to make 1, or make 2 and freeze the extra portion.
2. Roll out the dough and line a 9 inch deep pie dish with the pie crust according to the recipe. Take care not to stretch the dough to fit the pa. Instead gently lift and guide the dough to fit the corners and edges of the pie dish. Follow the recipe to trim the edges and roll the excess dough and create the pie crust. Flute or crimp the edge according to your preferences and let the pie crust chill in the fridge for at least 30 minutes.
3. Preheat the oven to 350°F / 180°C while the crust is chilling and place the oven rack in the lower third of the oven, along with a half sheet pan on the rack to preheat with the oven. The sheet pan should heat in the oven for about 30 minutes, so that it's nice and hot.
4. Line the inside of the pie dish with aluminum foil (dull side touching the crust). Make sure the foil is flush against the dough. Use two pieces and overlap them so that the whole crust surface is covered well.
5. Fill the lined pie crust with rice or sugar (to use as pie weights), and bake in the oven for 50 - 60 minutes. The edges will be a light blonde color.
6. Remove from the oven and then carefully remove the foil with the rice or sugar. Prick the bottom of the crust with a fork and return it to the oven without the pie weights.
7. Bake for about 10 minutes until the crust starts to turn golden in color.
8. While baking, whisk the egg or egg white to use as egg wash.
9. Remove the pie crust from the oven and quickly brush the inside of the crust with the egg wash. Make sure the egg wash coats the whole surface and the crust edge.
10. Return the pie plate to the oven and bake for a further 5 - 10 minutes until the crust turns a shiny golden brown.
11. Remove from the oven and let it cool to room temperature.

Separating the eggs

1. Separating the egg yolks from egg whites - It'll be easier to separate the eggs if they are cold. It's important to take care when separating the egg yolks from the whites because the egg whites can be used to make the meringue.
2. Carefully separate the egg whites, making sure not to contaminate the egg whites with ANY egg yolk. Place 4 of the egg whites in a clean, dry container with an airtight lid (with no traces of fat).
3. Place the egg whites in the fridge until you need them. Place all the egg yolks in another bowl.

Lemon filling

1. Mixing the ingredients - In a saucepan, place the sugar, salt, and cornstarch. Whisk together to combine well.
2. Add the egg yolks and whisk until the mixture is smooth and a little pale in color.
3. Next, stir in the lemon juice, and finally add the butter.
4. Heat the egg yolk mixture on medium-high heat while continuously whisking. When the butter has melted, lower the heat to medium. Keep heating the mixture while whisking, making sure to reach the corners to prevent the egg yolks from scrambling.
5. While whisking, take short breaks to check if the mixture is bubbling. When the mixture starts to bubble, that means the filling is hot enough and is boiling. This usually takes me 5 - 7 minutes, but the time will vary depending on your pot and stove.
6. Lower the heat to medium low, and keep cooking the mixture while whisking for a further 3 - 5 minutes, until the lemon filling is thick.
7. Remove from the heat, and pass the filling through a sieve.
8. Let the mixture cool slightly, but it should still be warm when filling the pie crust.
9. Whisk the warm lemon filling really well with a whisk, or a stick blender (which is what I prefer).
10. Pour the mixture into the cooled pie crust, and spread it evenly on the crust. Make sure the surface is as smooth as possible. Cover the filling with plastic wrap, making sure it's touching the whole surface of the filling.
11. Chill in the fridge until it sets and is chilled - at least 6 hours, preferably overnight.

Meringue topping

1. Make the meringue topping a few hours before serving, for best results.
2. Take the egg whites from the fridge and let them come to room temperature for best results. Make sure to clean and dry all pots, bowls, and utensils that will be coming into contact with any of the meringue ingredients. There should be no traces of fat on them.
3. In a saucepan, place the sugar and water. Mix the water and sugar until all the sugar is saturated with the water.
4. Heat over medium heat to dissolve the sugar. Swirl the pot to help dissolve the sugar. Do not use a spoon to mix the sugar syrup.
5. When all the sugar has dissolved and the water comes to a boil, cover the pot with a lid for 1 - 2 minutes. The condensation will wash down any sugar crystals on the sides of the pot. OR, use a pastry brush dipped in cold water to brush the sides of the pot to wash down any sugar crystals.
6. Remove the lid and continue to cook the sugar syrup until it reaches 240°F - or firm ball stage on a candy thermometer. Remember to check several spots (to eliminate the effect of uneven hot spots).
7. While the sugar syrup is cooking, place the egg whites, cream of tartar, and salt in a clean and dry mixing bowl, with a clean whisk attached to the stand mixer.
8. Whisk for a few minutes until the egg whites become frothy.
9. When the sugar syrup reaches 240 - 242°F, remove it from the heat.
10. While running the mixer on medium high speed, gently stream in the sugar syrup to mix in with the egg whites.
11. Once all the sugar syrup is added, keep whisking the meringue until you have stiff peaks (i.e. when you hold up the whisk with a small meringue peak, the peak stays up).
12. The meringue can be used when it's is at this stage. However, if the meringue is still hot, keep whisking until it’s only just warm.

Finishing the pie

1. Remove the pie from the fridge and then remove the plastic wrap.
2. Spread some of the meringue in a thick layer over the surface of the lemon filling. Pile up more meringue in the center to create a mound of meringue that is thicker in the middle. Create swirls with a palette knife.
3. Alternatively, scrape the meringue from the bowl into a piping bag IF you want to pipe the topping in a pattern instead, with a piping tip of your preference.
4. Use a kitchen blow torch to carefully caramelize the meringue just before serving.
5. If you do not have a blow torch, you can caramelize the meringue in the oven, but the meringue topping should be more even on the surface to help caramelize it evenly.
6. Set the oven to the broil function (medium heat). Keep the pie on a baking tray and place it in the oven. The rack should be in the middle, or just above the middle, making sure it's not too close to the top element, where it may burn easily.
7. Keep the oven door slightly ajar while the meringue caramelizes. Rotate the pie if needed to allow for even caramelization.
8. Remove from the oven and transfer to the fridge to let it cool down before serving.
9. The pie can be refrigerated for about 1 - 4 hours before serving.