Start by rolling out your pie dough to a 12-inch diameter. Carefully roll it up with your rolling pin, and place it in a 9-inch pie dish. Use your fingers to press the dough along the sides of the dish, ensuring it’s snug.
Optionally, take the second dough and cut strips to lay across the top of the dish. Pinch the edges to crimp them together, ensuring a beautiful finish.
Put the pie crust in the refrigerator for at least 30 minutes, or up to 3 hours. This will help the crust maintain its shape while baking.
Preheat your oven to 400°F. Remove the crust from the fridge. You can use pie weights or fill the crust with parchment paper and dried beans to prevent it from puffing up. Bake for 17 minutes.
Once baked, carefully take out the weights or parchment and use a fork to poke holes across the bottom of the pie crust. Place it back in the oven and bake until lightly browned, about another 10 minutes. Remove and set aside.
In a medium-sized pan, add water and lemon juice. Stir in corn starch and whisk until fully dissolved. Add in sugar and continue whisking until it dissolves.
Turn the heat to medium-high, whisking continuously until the mixture comes to a boil. Simmer for exactly 1 minute while whisking constantly until it thickens.
Remove from heat and ladle about ⅓ of the corn starch mixture into the egg yolks, whisking constantly to temper the eggs. Then, add the tempered yolks back into the pan.
Place the pan back on medium heat and whisk often until it simmers for another minute. Look for big crater-like bubbles forming on the surface.
Remove from heat and stir in butter and lemon zest. Pour this luscious filling into the pie crust.
Turn your oven down to 375°F. In a large bowl, whisk the egg whites with cream of tartar until foamy. Gradually add in sugar while mixing on high speed until stiff peaks form.
Spread the meringue on top of the warm lemon filling, using a small knife or spatula to create peaks.
Bake the pie for 10 minutes, just until the tips of the meringue start to brown. Keep a close eye to prevent burning!
Finally, chill the pie for at least 4 hours before serving. This allows the filling to set and the flavors to meld.
