In a small bowl, whisk eggs, sugar (if using) soy sauce and mirin together.
Heat a non-stick frying pan, dip folded paper towel in oil and apply oil to frying pan (be careful not to burn your hands)
When the pan is hot, reduce the heat to medium. Pour the egg mixture into the pan and quickly swirl it around the pan until the bottom of the pan is evenly covered. If the heat is too high and the egg is cooking too fast remove from heat.
When the egg is cooked half way, place the nori in the middle of the egg egg mix.
When the egg is set but not fully cooked, fold both sides of the egg mix towards the centre of the nori.
Roll from one side to the other side while gently pressing down to create nice Tamagoyaki shape.
Remove from the frying pan and set aside to cool for a few minutes. Cut Tamagoyaki into 2-3 pieces.