Preheat the oven to 375 degrees.

Separate the eggs, placing the whites into a medium sized mixing bowl, and the yolks aside to be used later.

Using an electric mixer, beat together the egg whites and cream of tartar until the egg whites start to become foamy. Start to add in the sugar, adding only one tablespoon at a time and beat until the mixture becomes thick, white, and glossy. Add in the vanilla and beat until stiff peaks form when you pull out the beater. Set this aside while you make the filling.

In a medium sized sauce pan, combine the sugar, cornstarch, and pinch of salt. Add the lemon zest, lemon juice, cold water and egg yolks and whisk thoroughly. Slowly pour in the boiling water and butter. Stirring constantly, cook over medium-high heat until the mixture comes to a boil. Let boil one minute.

Divide the filling equally into 4  bowls. Each part will be about 3/4 cups.  Add one to two drops of food coloring to 3 of the bowls, stirring well to disperse the color. Leave the 4th bowl as it is. Layer the colored lemon filling in the prepared pie crust.

Spread the meringue over the hot filling, taking care to spread the meringue completely to the edges of the pie.

Place the pie in the oven and bake at 375 degrees for 10-12 minutes or until the meringue is set and the tops of the peaks are lightly browned.

Cool completely on a wire rack and serve.