Dashimaki Tamago is similar to tamagoyaki, but using dashi for extra liquid in its ingredients. Dashimaki tamago has milder taste compared to usual tamagoyaki. However it is more difficult to roll because of the texture.
Mix dashi stock, shoyu, sugar, and mirin in a bowl. (we will call this seasoning mixture)
Whisk together eggs in a bowl until thoroughly blended, then add the seasoning mixture. Whisk again to combine.
Pour the oil into the pan on medium heat and use a small wad of paper towel to spread the oil to evenly coat the pan and to soak up the excess.
Pour 1/4 of the egg mixture in and let it cook.
When the egg is half way cooked but there's still some liquid egg on top, gently flip and start rolling the dashimaki tamago from the edge closest to you towards the back of the pan. When you reach the edge, slide the roll back to the edge closest to you.
Pour another 1/4 of the egg mixture into the pan. Gently lift the roll and let the egg mixture run under the roll.
Repeat from steps 5-6 until you've used all the egg.
Let the dashimaki tamago rest for 3 minutes, then slice it to your preference.