Place margarita mix, lime juice along with sugar into medium sauce pan, heat until it simmers (tiny bubbles on the outside edge of saucepan).

Add butter and heat until melted.

Mix egg yolks in medium bowl with whisk.

Add in coloring

Take saucepan off heat and slowly pour mixture into egg yolks mixing continually so the eggs don't scramble.

Return mixture to saucepan and heat for one more minute or until the mixture coats the back of a spoon.