200 grams unsalted butter chilled and cut into small squares
*optional red food coloring (6 drops)
3/4 cup sugar
3 eggs whites
Pinch of cream of tartar
Let's get Cooking...
For the filling, place egg yolks, sugar and zest in a saucepan and whisk until well combined. Combine cornstarch with 1/2 cup water in a small bowl and then add to saucepan along with the lemon and grapefruit juice. Food coloring? Add in butter. Place over medium heat and whisk constantly for 5-6 minutes until thick (do not let boil). Immediately pour into pie dish and spread to the edge. Cool and refrigerate.
To make the meringue combine sugar with 1/3 cup water in a small saucepan and stir over medium heat until the sugar dissolves. Brush down the sides of the sauce pan with a pastry brush dipped in water to remove any sugar crystals. Increase the heat to high and bring to a boil. Brush down the pan occasionally until the mixture reaches thread stage (230F). At this point put the egg whites and cream of tartar in a bowl and mix with an electric mixer until soft peaks form. Continue cooking to sugar to hard ball stage (244F) and then, with the beaters on, gradually pour the sugar mixture into the egg whites in a steady stream. Whisk constantly for 6-7 minutes.