Make the pie crust

1. In a large bowl, mix the flour, powdered sugar, and salt.

2. Add the cold butter and rub it in with your fingertips until the mixture looks sandy.

3. Pour in the cold water and mix just until the dough comes together.

4. Shape into a flat disc, wrap in plastic, and chill for 30 minutes.

5. Roll out the dough on a floured surface or between parchment paper.

6. Grease a 25 cm (10-inch) tart pan and line it with the dough. Prick the bottom with a fork to prevent puffing during baking.

7. Freeze the crust for 1 hour (or overnight).

8. Preheat the oven to 180°C (350°F) and bake for about 30 minutes, until lightly golden. Let cool.

Make the lemon filling

1. In a saucepan, whisk together the sugar, cornstarch, and salt.

2. Add the water, lemon juice, and zest. Cook over medium heat, stirring constantly for about 7 minutes, until thickened and starting to bubble.

3. In a separate bowl, whisk the egg yolks.

4. Gradually stir a bit of the hot mixture into the yolks to temper them, then pour everything back into the pan.

5. Cook for another 5–7 minutes, stirring, until thick and gently simmering.

6. Remove from heat. Add the butter and vanilla, and stir until smooth.

7. Strain the filling through a sieve, then pour into the baked crust.

8. Cover and refrigerate for at least 4 hours or overnight.

 Make the Swiss meringue

1. In a heatproof bowl, combine the egg whites and sugar.

2. Place over a pan of simmering water (double boiler) and whisk constantly until the sugar is dissolved and the mixture is warm to the touch.

3. Transfer to a stand mixer and whisk on high speed until stiff, glossy peaks form and the bowl is no longer warm.

4. Spread the meringue over the chilled pie, creating swirls and peaks.

5. Toast with a kitchen torch, or place under the broiler for 1–2 minutes until lightly golden.

6. Serve chilled and enjoy!