*You can use less truffle salt, e.g. 1/3 tsp., depending on your taste.
In a small bowl, thoroughly mix the horseradish powder and vinegar until blended. Next, stir in butter until it forms a smooth paste. Stir in the remaining ingredients excluding the eggs. Set aside. Slice eggs in half lengthwise and remove yolks, leaving whites intact. Add yolks to the butter mixture. Mash together with a fork until smooth. Pipe egg mixture into the whites.