To make the crust: Heat the oven to 425 F. In the bowl of a food processor, combine the flour, sugar, salt and butter. Pulse until the mixture resembles coarse crumbs, about 7 to 10 pulses. Run the processor while slowly pouring in the cold water until the dough just comes together.

Transfer the dough to a surface, pat into a disc and wrap in plastic wrap. Refrigerate for 30 minutes. Unwrap the dough. On a lightly floured surface, roll the dough into a ¼-inch-thick circle. Transfer the dough to a pie pan and press the dough into the pan. Trim the edges of the dough so that ½ inch hangs over the edge of the pan. Fold the edge of the dough under itself to create a thicker rim, and flute the crust as desired. Freeze for 20 minutes.

Line the pie crust with parchment paper and fill with pie weights. Bake for 15 minutes. Remove the pie weights and parchment, lower the oven temperature to 375 F and bake for an additional 15 to 20 minutes until the crust is golden brown. Let cool to room temperature while you make the filling.

To make the filling: In a pot, combine the water, lemon juice, zest, sugar, cornstarch, salt and egg yolks. Heat over medium heat, whisking constantly, until bubbling, 6 to 8 minutes. Allow the mixture to simmer for 2 more minutes while whisking. Remove from heat and stir in the butter until melted.

Pour the filling through a wire strainer directly into the pie crust. Refrigerate until fully set, 4 to 6 hours or up to overnight.

To make the meringue: In a small pot, heat 2 inches of water until simmering. In the bowl of a stand mixer, combine the egg whites, sugar, salt and cream of tartar. Set over the water so the bottom of the bowl doesn’t touch the water. Heat, whisking constantly, until the sugar is dissolved and the egg whites are warm, about 2 to 3 minutes.

Transfer the mixer bowl to the stand mixer fitted with a whisk attachment. Whisk on high until stiff peaks form, 6 to 8 minutes. Spread the meringue onto the chilled pie. Using a torch, toast the meringue until golden brown, if desired.