Lemon Meringue Pie

Mix 180g all-purpose flour and 1/4 tsp fine sea salt in a large mixing bowl. Cut in 113g cold cubed butter (reserved for the crust) with a pastry cutter until the mixture forms coarse crumbs with pea-sized butter chunks. Drizzle in 3-4 tbsp ice water 1 tablespoon at a time, mixing gently until the dough just holds together with no dry flour spots. Shape dough into a 10cm flat disc, wrap in plastic wrap, and chill in the refrigerator for 30 minutes. Roll chilled dough to a 30cm circle on a lightly floured surface, press firmly into a 9-inch (23cm) glass pie dish, trim edges to a 2cm overhang, and crimp decoratively. Line the crust with parchment paper, fill with ceramic pie weights or dried beans, and bake at 190°C (375°F) on the middle oven rack for 15 minutes. Remove parchment and weights, bake 5 more minutes until the crust is pale golden, then set aside to cool slightly.

In a medium heavy-bottomed saucepan, whisk 200g granulated sugar (for the filling), 30g cornstarch, and remaining 1/4 tsp fine sea salt until fully combined. Slowly whisk in 240ml cold water and 180ml fresh lemon juice until completely smooth with no lumps. Cook over medium heat, stirring constantly with a silicone spatula, for 4-5 minutes until the mixture reaches a rolling boil and thickens to a smooth, pudding-like consistency. Remove the pan from heat.

In a small heatproof bowl, whisk 4 egg yolks and 1 whole egg until smooth. While whisking the eggs constantly, slowly pour 120ml (1/2 cup) of the hot lemon mixture into the bowl to temper the eggs and prevent curdling. Pour the warmed egg mixture back into the saucepan with the remaining lemon base, stirring constantly. Return the pan to medium-low heat, cook for 2 minutes until the mixture returns to a gentle boil, then remove from heat. Stir in 28g cut butter (reserved for the filling) and 2 tbsp lemon zest until butter is fully melted and incorporated. Pour the warm filling directly into the slightly warm pre-baked pie crust, spread into an even layer, and set aside.

Place 4 room-temperature reserved egg whites and 1/4 tsp cream of tartar in a completely clean, dry stand mixer bowl (use a hand mixer if you do not have a stand mixer). Whip on medium speed for 1-2 minutes until soft, droopy peaks form when the whisk attachment is lifted. Increase mixer speed to medium-high, add 100g granulated sugar (for the meringue) 1 tablespoon at a time, waiting 10 seconds between each addition to let sugar fully dissolve. After all sugar is added, continue whipping for 3-4 minutes until stiff, glossy peaks form (peaks stand straight up with no floppy tips when the whisk is lifted), then stir in 1/2 tsp vanilla extract.

Spoon the freshly whipped meringue directly onto the warm lemon filling, starting at the crust edges first to seal the meringue completely to the crimped crust to prevent shrinking or weeping. Spread meringue across the entire surface to the edges, then create decorative swirled peaks with the back of a spoon. Bake at 175°C (350°F) on the middle oven rack for 12-15 minutes, until the meringue peaks are evenly light golden brown.

Remove the baked pie from the oven, transfer to a wire cooling rack, and let it cool completely at room temperature for 2 hours. Transfer the pie to the refrigerator to chill for at least 4 hours (preferably overnight) to let the lemon custard set fully. Do not cut the pie early, as the filling will be runny if not properly chilled. Serve chilled, garnished with an optional twist of fresh lemon zest if desired.