Boiled eggs are delicious when eaten with salt, but you can experience a distinctive flavor with Nitamago. Japanese seasonings give the egg whites a rich taste that complements the yolks well. This dish is also known as 'Ramen Egg' outside of Japan.
Fill a large pot with plenty of water and bring it to a boil. Once it comes to a boil, reduce the heat to medium and carefully add the eggs, which should be fresh from the refrigerator, one at a time using a ladle. Boil them for 7 minutes or for your preferred duration.
After boiling, promptly cool the eggs with cold or running water to minimize residual heat. Then, peel off the shells.
Mix the seasonings (sake, mirin, sugar, and soy sauce) in a small pot and bring it to a boil. Once it comes to a boil, turn off the heat and let it cool down. It is more efficient to start preparing while the eggs are boiling.
Place the boiled eggs and the seasoning mixture in a ziplock bag and seal it, removing as much air as possible. Let them sit in the refrigerator for 2 hours. (The longer you let them soak, the stronger the flavor will become.)