Mix mustard, sugar, salt and pepper in a pan. Add vinegar and whisk to blend well. Add cream and egg yolks to the pan, put over low heat land cook,stirring til thickened and smooth. Serve. Makes 2 1/2 cups. Store any leftover sauce in refrigerator for 1 to 2 days.
It will thicken up like mayonnaise and makes an unbelievably good spread for ham sandwiches. A little side note: The cardinal sin when cooking a ham, not matter what kind, is heating it at too high a temperature for too long. The secret is low oven temp, 275, til it reaches an internal temperature of 135, which can take as long as 6 hours. Let ham rest for 15 to 30 minutes before carving.