1 cup (approximately) freshly grated horseradish root
salt to taste
1/3 cup truffle oil or substitute olive oil
Leave the rubber band on the bottom of the parsley. Wash upside-down and, holding the parsley by the stem with tongs, blanch in boiling salted water for about 10 seconds. Rest in ice water and press out the water after it’s cooled down. Chop leaves and pat dry with a towel.
Put leaves into a blender and add an equal part grated horseradish. Salt to taste and add truffle oil. Blend until smooth and combined to make an even puree. Add a small amount of water if necessary to thin to sauce consistency.