Horseradish powder is a spicy, hot powder that is normally mixed into cream or egg based sauces, like mayonnaise, sour cream or crème fraiche, to produce very “hot” dipping sauces. You get horseradish powder by using only the root, which is dried and then finely ground to produce horseradish powder. You are more likely to see horseradish power mixed into various spreads than you are to find it in the powdered form. But many now search for the powder so they can decide the level of heat and flavoring they’d like in a sauce.
(reprinted from wisegeek.com)
