Here’s how to create Shoyu Tamago in just a few simple steps:

1. Prepare the Marinade: In a bowl, combine soy sauce, mirin, water, and sugar (if using). Stir until the sugar dissolves completely.
2. Boil the Eggs: In a pot, bring water to a rolling boil. Carefully add the eggs and boil them for about 6-7 minutes for a soft texture.
3. Ice Bath: While the eggs are boiling, prepare an ice bath in a bowl filled with ice and cold water.
4. Transfer Eggs: Once boiled to your liking, transfer the eggs immediately to the ice bath and let them cool for about 5-10 minutes.
5. Peel the Eggs: Gently crack the shell and peel the eggs under running water for easier handling.
6. Marinate: Place the peeled eggs in a container and pour the marinade over them. Ensure they are fully submerged. If needed, use a small plate to weigh them down.
7. Chill: Let the eggs marinate in the refrigerator for at least 30-40 minutes. The longer they sit, the more flavor they absorb.
8. Serve: After marinating, remove the eggs from the liquid. Cut them in half and discard the marinade.

These steps will allow you to create incredibly flavorful Shoyu Tamago with minimal fuss.