Follow the steps in order for the best result.
Begin by preheating your oven to 350°F (175°C).
For the filling, grab a medium saucepan and whisk together 1 cup of caster sugar, 2 tablespoons of plain flour, 3 tablespoons of cornflour, and 1/4 teaspoon of salt. Incorporate the zest and juice from 2 unwaxed lemons, along with 1 1/2 cups of water. Place the saucepan over medium heat and cook until the mixture just begins to boil. Then, stir in 2 tablespoons of butter.
In a separate bowl, thoroughly beat 4 egg yolks. Gradually add a cup of the hot sugar mixture to the beaten yolks, whisking continuously. Return this mixture to the saucepan. Bring to a boil, stirring constantly until the filling thickens. Remove from heat and pour the lemon filling into your prepared 9-inch pie crust.
Time for the meringue! Ensure your large mixing bowl is impeccably clean – wipe it down with lemon remains and dry with a paper towel to eliminate any traces of grease or residue. Whisk 4 egg whites until they become foamy. While this can be done by hand, an electric mixer yields the best meringue. Gradually add 6 tablespoons of caster sugar, whisking until stiff peaks form. You can test this by holding the bowl upside down – the meringue should hold its shape!
Also, check that all the sugar has dissolved by rubbing a small amount of meringue between your fingers. If it feels grainy, continue whisking for a few more minutes. Once smooth, gently spread the meringue over the warm pie filling, ensuring it reaches all edges and seals any gaps. Create decorative peaks across the meringue for those delightful chewy bits.
Bake in the preheated oven for about 10 minutes, or until the meringue turns a beautiful golden brown.
For the ultimate experience, allow the pie to cool slightly before refrigerating for a few hours. Serve chilled with a dollop of cream or a scoop of ice cream. (Remember to factor in chilling time for optimal enjoyment!)