Mom's Homemade Mustard Sauce

1/4 C Ground Mustard

1/2 C Sugar

1/2 C Vinegar

1 beaten egg

Salt and Pepper to taste

1 C Mayo

Add mustard and sugar to a saucepan and mix. Add vinegar, egg and salt and pepper and cook over medium heat until sauce coats the back of a spoon, about five minutes.

Cool completely, then add 1 C mayonnaise. 

Great with corned beef or ham.