Still using whisk, gradually blend in cold water, then lemon juice until smooth.  Add beaten egg yolks, blending very thoroughly.  Add butter.

Add boiling water gradually stirring constantly with flat sided spoon.

Gradually bring mixture to full boil, stirring gently and constantly over medium to high heat.  Reduce heat slightly as mixture begins to thicken.  Boil slowly for 1 minute.

Remove from heat and stir in grated peel and food coloring.

Pour hot filling into pastry shell.  Let stand while preparing meringue.

Have egg whites at room temperature.  Use a small, deep bowl.  Beat with electric mixer several seconds until frothy.  Add cream of tartar.  Beat on high speed until soft “peaks” form.  Reduce speed to medium and add sugar one tablespoon at a time.  Return to high speed until fairly stiff and glossy and soft “peaks” form again when beaters are withdrawn.

Place meringue on the hot lemon filling, spread to the edges and form pretty peaks with spatula.

Bake at 350 degrees for 12-15 minutes, until golden brown.

Cool on rack for 2 hrs before cutting and serving.  Refrigerate any leftovers.