In a measuring cup, crack in 4 eggs and whisk until smooth. Make sure to whisk throughly. This will take a few minutes.
Once egg is smooth, mix in rest of the ingredients: mirin, sugar, dashi powder, salt. Mix well until sugar and dashi powder is fully dissolved.
In a rectangle pan, turn on heat to low and oil entire pan. Wipe off excess oil with a paper towel.
Pour a thin layer of tamagoyaki mixture (about half centimeter in height). Pop any air bubbles you see.
Once it is 80% cooked, start rolling the opposite side of the egg towards you. With every roll, make sure to put a little pressure so the eggs stick together
Once you roll the egg towards you, you should have a little egg roll.
Push the egg to the opposite side
Oil pan and wipe off excess.
Then pour the egg mixture about half cm in height.
Lift the cooked egg so the egg mixture can seep beneath it. This will create a seamless roll.
Once 80% cooked, roll the cooked side of the egg over onto the new egg mixture. Put a little pressure again to flatten out the top. You should start to see a rectangle shape forming.
Roll over again until you reach the end of the pan closest to you.
Slide the cooked egg to the opposite side and repeat the process 3-4 more times until the egg mixture is gone.
By the end of the egg mixture, you should get a rectangle shaped egg omelet.
Remove off heat and let it cool before cutting
Once it cools down a bit, slice into quarter inch thickness and plate
Serve as a side dish or put in bento and enjoy!