Prep. If you have raw horseradish root, wash it thoroughly and with a peeler, scrape it until only milky while shows. Then grate it fine or beat the heck out of it in a processor or blender. Add just enough distilled white vinegar to make it slushy and spreadable, and then a pinch of salt to taste. I've tried it with other vinegars and the results are very good, but not as versatile. Let it age a few hours to reach a full gallop.
Mix all the ingredients and taste. Add more of whatever you want. Try to refrigerate for at least 30 minutes to allow them to mingle properly.
Serve. Enjoy the horseradish cream sauce with steaks, smoked salmon, roast beef sandwiches, and so much more.