Grandpa's Finnish Christmas Mustard

1/2 cup Coleman's dry mustard 1/2 cup sugar 2 1/2 Tablespoons potato starch (I often substitute corn starch for potato starch, but today I happen to have potato starch in the cabinet) 1/2 cup cream 1-4 Tablespoons apple cider vinegar

Mix the dry ingredients together and sift into a heavy bottomed kettle. Add the cream and mix well. Heat over a medium heat, stirring and scraping the bottom constantly until it. Take the pan off the heat and add at least a Tablespoon of vinegar. You can add more if you like, the vinegar makes the mustard more sour and a thinner consistency. Put the mustard in a bottle while warm. Keep in the mustard in the refrigerator. Warning: Do not let the sauce boil because the potato (or corn) starch will thicken and become like glue!

The recipe also says to experiment and add a little cognac or whiskey.