Add enough cold water to cover eggs by about 1 inch. Bring to a boil. Cover, and remove from heat.
Let stand 13 minutes.
Drain, and transfer eggs to ice-water bath until cold.
Peel eggs, and halve lengthwise.
Transfer yolks to a medium bowl, and mash with a fork until smooth. Stir in mayonnaise, wasabi, vinegar, and scallions. Season with salt. Pipe or spoon filling into whites.