Using a 9-inch round x 1-1/4 or 1-1/2-inch deep pie dish, make the pie crust as instructed at the above link (or linked in the above paragraphs). To learn how to scallop the edges of the crust, view the How to Easily Scallop Pie Crust Edges Video. Parbake/blind-bake the crust at 425ºF for 15-20 minutes depending upon the crust you are making. (After parbaking, use an egg wash made of egg yolk and heavy cream.) Then continue to bake. If you're just parbaking 15 minutes, you may add the egg wash prior to any baking. Once baked, set on a wire rack to cool.
If you would like to create a deeper, richer yellow color, stir together 1/4 teaspoon turmeric, 1/4 teaspoon cornstarch, and 1 teaspoon water. Whisk in a little at a time to the lemon curd until it reaches your desired color. Continue to cook over medium heat while adding this mixture. (See the video on How to Naturally Color Lemon Curd.)
If you do not wish the filling to be thin when at room temperature, mix in water and unflavored gelatin. To do so, add 1 teaspoon gelatin to 2 tablespoons room temperature water, stir, and allow to rest for 1 minute. Add 2 tablespoons boiling water, stir; set aside to cool. Then, stir the gelatin mixture into the lemon curd.
In a small saucepan over medium heat, bring the remaining 1/2 cup sugar, 2 tablespoons water, and lemon juice to a boil. Do not stir. Once the mixture reaches 245ºF, remove it from the heat and stir until the sugar dissolves. If any sugar granules get on the sides of the saucepan, brush them downward using a pastry brush dipped in water. (Sugar granules sometimes crystallize and ruin the syrup.)
Turn the mixer to medium speed and drizzle in the sugar-syrup about 1-1/2-inches away from the sides of the bowl. Continue to beat for about 6 minutes or until the bowl cools down. (Stainless steel bowls take about 6 minutes. However, a glass bowl may take less time.) Watch this video on The Consistency of Sturdy Meringue.
If desired, using a kitchen torch, brown the top of the meringue. See the How to Torch Meringue Video.
Refrigerate until ready to serve. (This keeps the filling firmer.)
*For a lower fat version, you may reduce the egg yolks to 4.