Step 1

Add 2 teaspoons potato starch and 1/4 teaspoon salt to a deep bowl and then pour in 2/3 cup stock. Whisk the mixture together until the salt has fully dissolved.

Step 2

Break 4 eggs into the bowl with the dashi (you can remove the chalazae if you want) and beat the eggs into the dashi until the mixture is uniform in color. Pass it through a fine-mesh sieve if you still see pockets of egg white after beating it for about a minute.

Step 3

Make the honey mustard sandwich spread by mixing 1 tablespoon mayonnaise, 1 teaspoon Japanese hot mustard, and 1 teaspoon honey in a small bowl until uniform.

Step 4

Heat a non-stick frying pan over medium-low heat and add 1 teaspoon vegetable oil. Use a paper towel and chopsticks to spread a thin, even layer of oil around the pan, and then use it to wipe out any beads of oil.

Step 5

Pour the egg mixture into the pan and let it cook until you see the bottom layer of the egg start to set (a few seconds).

Step 6

Start scrambling the egg, making sure you work your way evenly around the pan. The idea is to scrape the cooked egg off the bottom of the pan and mix it with the raw egg on top.

Step 7

Once the egg starts thickening to the point it doesn't want to immediately level itself off, shake the pan to level off the top of the egg, cover it with a lid, and then turn down the heat all the way. Steam the egg for 2 minutes.

Step 8

Once the timer is up, open the lid and start folding the tamagoyaki from the top, working around the omelette and folding the edges towards the center like an envelope.

Step 9

Use two spatulas to shape the egg into a rectangle with the same shape and size as your bread. Once you're happy with the shape, cover the pan with a lid, turn off the heat, and let the omelette steam for another minute or until the egg is fully set.

Step 10

Spread a generous layer of the honey mustard sauce on 2 slices sandwich bread, and when the egg is cooked, place it on one side of the bread.

Step 11

Cover the Dashimaki Tamago with the other slice of bread and place a flat-bottomed plate or tray on top of the sandwich to lightly press it down and help the bread and egg conform to each other.

Step 12

You can serve your Japanese egg sandwich as is or cut the crusts off to give it a nicer shape.