Adjust the amount of salt depending on the shiro-dashi (Step 9).
Combine the mirin and shiro-dashi in a bowl and mix in the katakuriko until there are no lumps.
Add the egg, and beat well until well-combined. Strain through a fine meshed sieve. It will be even better if you strain it through a cheesecloth.
Moisten and tightly wring out a kitchen towel, fold it and put it next to the stovetop. Heat oil in frying pan over medium heat. When the pan is hot, wipe excess oil in the pan with a paper towel.
Put the bottom of the frying pan for a second on the moistened kitche towel to even out the heat. Put 1 ladleful of the egg mixture in the pan, and tilt the pan to spread it out.
Cook over very low heat as if you're drying out the egg. When the top is dry, peel the omelette off the pan using a skewer.
Line a sieve with paper towel and transfer the omelet. Let cool. The omelets will stick to each other, so don't stack them.
To make kinshi tamago (shredded omelette), discard the crispy bits around the edges, roll it up and slice as thinly as possible
Untangle gently with your hands as if you're fluffing them up.
Adjust the amount of shiro-dashi depending on the brand, since the saltiness varies. A basic ratio is 1 teaspoon of shiro-dashi to 2 teaspoons of water.
Mirin adds sweetness, so the sugar is optional. Mirin or sugar make the omelette more likely to burn, so watch the heat carefully.
Situation to avoid No. 1:
If you don't completely dissolve the katakuriko, or leave the egg mixture sitting around for too long, you'll get white lumps.
Situation to avoid No. 2:
If the frying pan is too hot, the omelette start cooking before it's been spread around the pan and will form lumps.
Situation to avoid No. 3:
If the temperature of the pan is too low, the egg mixture won't spread evenly and only the middle will cook, forming lumps.
A recipe using usuyaki tamago: (Recipe ID: 969997)
Another recipe using usuyaki tamago: (Recipe ID: 1099612)
A recipe using kinshi tamago: (Recipe ID: 1052729)
This is another festive sushi recipe that uses kinshi tamago (Recipe ID: 1052927).
Here's another recipe using kinshi tamago: (Recipe ID: 1167810)
Story Behind this Recipe
I received feedback on my omurice (rice omelet) recipe I uploaded previously that people had trouble making the usuyaki tamago (thin omelette), so I've uploaded this recipe, explaining the conventional way to make it as well as some tricks I've discovered over the years.
Each omelette is the size of the bottom of the frying pan. You can make 1 omelette with 1 ladleful of egg. Once you add the egg to the pan, cook it over very low heat as if you're drying it out. Shred the omelette for kinshi tamago once it's completely cooled using a sharp knife. The sieve shown in Step 6 is a bit small. Use a large one if you have one available.