Mix the sugar, mustard and salt together in a
medium size bowl. In a separate bowl, beat the
eggs, then add them to the dry ingredients.
Heat the vinegar to boiling and pour slowly
over the egg mixture, stirring constantly.
Add the butter and continue stirring until
all the butter has melted.
Allow the mixture the cool to room temperature,
then use a wire whisk to mix in the mayonnaise.
Add a few drops of yellow food coloring if desired.
Makes about 1 1/2 c. of dressing.