Steps

1. Crack 3 eggs into a plastic container and whisk until the yolks and whites are fully combined. (Key Tip!) Leaving clumps of egg white can lead to uneven cooking and an unappealing appearance, so whisk thoroughly until it looks completely homogenous.
   🕒 00:28
2. Lightly oil the inside of the plastic container where the egg mixture will be poured, using a paper towel dipped in a small amount of oil. (Key Tip!) Oiling prevents the egg from sticking and makes cleanup much easier.
   🕒 01:07
3. Add 2 pinches of salt and 1.5 tsp of sugar to the whisked eggs and mix.
   🕒 01:55
4. Stir in 4 tbsp of milk. (Key Tip!) Adding milk creates a fluffy texture and makes the sandwich exceptionally delicious. If you don't have milk, you can substitute with soy milk, almond milk, or water.
   🕒 02:10
5. In a separate small bowl, mix and dissolve 1 tbsp of Mirin (Sweet Rice Wine) and 1 tsp of Potato Starch. Add this mixture to the egg mixture and stir well. (Key Tip!) Dissolving potato starch in mirin before adding prevents lumps and helps retain the moisture from the eggs and milk, ensuring a fluffy result.
   🕒 02:30
6. Cover the plastic container with the egg mixture and set aside.
   🕒 03:05
7. In a bowl, combine 1 tbsp of Mayonnaise and 2g of tube mustard and mix well. (Key Tip!) The tanginess of the mustard and mayonnaise adds a nice accent and enhances the overall flavor.
   🕒 03:08
8. Lay out 2 slices of 8-slice thickness bread on plastic wrap. Spread the prepared mustard-mayonnaise mixture evenly on both sides of each slice. (Key Tip!) Applying mayonnaise prevents the moisture from the filling from soaking into the bread. Using slightly chilled bread is recommended as it won't become too soft.
   🕒 03:29
9. Lightly shift the lid of the plastic container with the egg mixture, give it a quick stir, and microwave on 600W for 1 minute and 30 seconds.
   🕒 04:22
10. Remove from the microwave and whisk the egg finely to even out the temperature. (Key Tip!) Microwave cooking can easily result in uneven heating. Whisking it thoroughly after the first heating ensures even cooking and improves the texture.
    🕒 04:40
11. Shift the lid slightly again and microwave on 600W for another 1 minute and 30 seconds.
    🕒 05:05
12. After heating, if the egg mixture on the surface is still very loose and moving, add an additional 10 seconds of heating at a time until it stops moving. (Key Tip!) If the surface is no longer loose but still slightly undercooked, it's fine as it will continue to cook from the residual heat.
    🕒 05:24
13. Transfer the fluffy cooked egg from the oiled plastic container onto one slice of bread.
    🕒 05:34
14. Place the other slice of bread on top of the hot egg and wrap the entire sandwich tightly with plastic wrap.
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15. Gently press down on the wrapped sandwich with your hands to avoid crushing the egg. Let it sit for 5 minutes to allow the bread and filling to meld together. (Key Tip!) The residual heat from the egg will warm the bread, integrating the bread and filling for an even more delicious result.
    🕒 06:08
16. After 5 minutes, cut the sandwich in half horizontally while still wrapped in plastic wrap to keep the bread from shifting.
    🕒 06:50