Begin by placing eggs in a saucepan and cover with cold water. Bring to a rolling boil over medium-high heat. Turn off heat, cover, and let sit for 10-12 minutes. Transfer to an ice bath for 5 minutes.

Once cool, tap each egg on the counter to crack the shell, then peel under running water to keep eggs intact.

Slice each peeled egg in half, remove yolks, and place in a bowl. Add mayonnaise, mustard, and any seasonings for variations. Mash until creamy.

Fill each egg white with the yolk mixture using a piping bag or spoon, mounding over the edges.

Garnish as desired based on the variation: sprinkle curry powder, top with dill or smoked salmon, or add bonito flakes and sesame dressing.