The Japanese egg salad sandwich (Tamago Sando) doesn’t try to be wildly different from the beloved Western classic. The egg salad itself is simple and humble as it should be, except Japanese mayonnaise (my favourite is Kewpie mayo) is used instead of regular mayonnaise. Without a doubt, the most distinctly Japanese feature in this popular rendition of Tamago Sando is the soft-boil egg halves in the center. Apart from being visually pleasing, the soft yolk adds richness to the overall experience. For die-hard fans of a gooey, jammy egg yolk, this is the ultimate egg salad sandwich!
Related: The Prettiest Japanese Fruit Sando
Bring the eggs to room temperature by placing in a bowl of tepid tap water and setting aside while you bring a medium pot of water to a boil. There should be enough water in the pot to just cover the eggs once they’re added to the pot.
Once water comes to a boil, use a slotted spoon to gently lower all six eggs into the water. Immediately start timer for 6 minutes 30 seconds. Prepare an ice bath large enough for the two soft-boiled eggs which will come out first. At 6 minutes 30 seconds, scoop two of the six eggs into prepared ice bath and immediately start timer for an additional 3 minutes for hard-boiled eggs. At the 3 minute alert, bring entire pot to the sink and tilt the boiling water out while running the coldest tap water over the four eggs for 20-30 seconds. Cover the eggs in cold water and set aside.
Peel the two soft-boiled eggs, handling gently as they are soft. Cut into halves, lengthwise. Wipe knife in between to get clean cuts.
Peel the four hard-boiled eggs. Chop into small dice or smash with a fork to your preferred size and texture. Place into mixing bowl and fold with mayonnaise, scallions plus salt and pepper to taste.
To assemble each sandwich: squeeze a squiggle of mayonnaise on one bread slice and a squiggle of mustard on the other.
Place cut halves of one soft-boiled egg, lengthwise and cut-sides down, vertically down the middle of one bread slice. Top with half the prepared egg salad mixture and gently spread to edges, leaving a slight border on the left and right sides. Top with other bread slice to form sandwich. Trim left and right crusts but leave the top and bottom crusts. Rotate sandwich 90 degrees so the sides with crusts are now on the left and right sides. Cut sandwich into equal thirds by making two vertical cuts through the sandwich (across the centers of each jammy egg half). Wipe knife in between to get clean cuts. Flip to reveal beautiful cut profiles! Repeat steps 5-6 to make a second sandwich.
Sprinkle with aonori (Japanese seaweed powder), if desired.