Chop peeled horseradish root into approximately 1/2 inch chunks, place in blender jar. Add white vinegar and pulse. Add more vinegar as necessary allow the blender to move the chunks around and grind them. Stop blending when your desired consistency is reached. Stand back and open the lid. I'm not kidding fresh grated horseradish is powerful stuff, don't let the fumes get in your eyes. Taste cautiously and be prepared for an amazing sinus clearing experience. Fresh grated horseradish is a hundred times more powerful than anything I have ever found in a bottle in the grocery store. It will tame down after a few days in the refrigerator.