In a medium saucepan, cover eggs with 1 inch of water. Bring to a boil; remove from heat. Cover and let stand for 12 minutes.
Drain eggs; run under cold water until cool enough to handle. Peel and halve eggs lengthwise; remove yolks and transfer to a bowl.
Mash with a fork; mix in mayonnaise, mustard, and vinegar. Stir chopped watercress and horseradish into yolk mixture. Spoon mixture into whites, garnish with watercress leaves.
Kindly Submitted by “Healthy Hilary”