Durkee's Famous Sauce

1/2 c cold water
4 T cornstarch
1/2 c plue 2 tb dark vinegar
2 T salt
1/2 c sugar
1 whole egg
4 T french's prepared mustard
4 T margarine -- tiny bits
Place all ingredients as listed in blender on high speed until
smooth (2 minutes). Transfer to top of double boiler and cook over gently
boiling water, stirring often for 12 to 15 minutes or until thickened
and smooth. Once more put mixture back through blender 30 seconds or
till smooth, using high speed. Refrigerate in covered container 24
hours before using. Keep refrigerated 3 months.