Crack eggs into a bowl and beat them with seasonings (dashi, mirin, and soy sauce).
Dip a small piece of folded paper towel in oil, then apply it to a tamagoyaki pan. Heat the pan over high heat. Once the pan is hot, pour about a quarter of the egg mixture (for 2 servings) into the pan.
If there are large air bubbles, pierce them and fill the holes with a small amount of the egg mixture. When the mixture is almost set but still slightly runny, roll it several times using chopsticks, folding it from front to back.
Move the rolled egg to the front of the pan. Apply oil from the small folded paper towel to the pan, and pour an equal amount of egg mixture as in step 2 into the pan.
Repeat the same process as in steps 3 and 4 until all of the egg mixture is used, increasing the layers of the rolled egg. Each time you pour the egg mixture, use chopsticks to lift the rolled egg, allowing the mixture to spread underneath it.
Once it is done, remove it from the pan before it overcooks from the residual heat.
(Optional) Place it on a sushi mat or paper towel and shape it nicely.
Cut it into 1-inch (2.5cm) pieces.
Garnish with grated daikon radish and soy sauce to taste.