In a bowl, beat the eggs and mix in the soy sauce, sugar, and dashi powder until fully combined.

Preheat a tamagoyaki pan over medium heat. Add the cooking oil and allow it to heat thoroughly.

Pour the entire egg mixture into the hot pan all at once. Immediately begin stirring vertically with chopsticks. As the egg thickens, you will begin to see the bottom of the pan appear briefly as you move the egg aside. Once the mixture is no longer runny and holds together, turn off the heat.

Use chopsticks to fix any small holes or uneven areas. Let it rest in the pan for about 20 to 30 seconds. If it still feels too soft to roll easily, turn the heat back to medium and cook the bottom for another 10 to 20 seconds. Turn off the heat and fold the egg into a three-fold roll.

Cook the rolled omelette for about 20 seconds on each side over medium heat.

Transfer the roll onto aluminum foil and wrap it tightly. Let it rest for 5 minutes. The residual heat will gently steam the inside so you don’t have to worry about precise heat control.

After 5 minutes, unwrap and slice into 6 equal pieces.