1/4 c. dry mustard
1/4 c. apple cider vinegar
1/2 c. mayonnaise
2 tbsp. sugar
1/8 tsp. salt
1 egg

Combine mustard, vinegar, sugar, salt and egg. Cook on low heat, stirring until thickened, about 2 minutes. Chill 10 to 15 minutes. Stir in mayonnaise. Good with ham.