Start boiling water: Fill a medium pot with enough water to cover all the eggs and bring it to a boil.
Make the marinade (see Note 2): In a separate pot, mix 2 tablespoons soy sauce, 2 tablespoons mirin, 1 tablespoon sake, 2 teaspoons granulated sugar, 1 teaspoon dashi powder, and ½ cup water. Heat it over medium-high until it boils, then turn off the heat and let it cool.
Cook the eggs: Once the water is boiling, lower the heat slightly so the bubbles become smaller and gentler. Then, gently add 4 large eggs straight from the fridge using a skimmer or spoon—make sure to slowly lower them in to prevent cracks! Start the timer as soon as the first egg goes in: 6.5 to 7 minutes for runny yolks, 8 to 9 minutes for firmer soft-boiled eggs (9 minutes is best for bento).
Chill the eggs: When the timer’s up, transfer the eggs to an ice bath for 10 minutes. Lightly crack the shells, especially at the top and bottom, then return them to the ice water for another 5 minutes or until the eggs are chilled completely.
Peel the eggs (see Note 3): Gently tap the eggs on the counter to create small cracks, then peel them in the water or under running tap water, using your thumb to lift off the shell bit by bit. Pat them dry.
Marinade the eggs: Place the peeled eggs in a plastic bag with the marinade and refrigerate for at least 7 hours (or up to 3 days). I think they taste best on the second day!
Notes
(Note 1)Choosing the right dashi powder: I highly recommend using high-quality dashi powder! My all-time favorite is Kayanoya Dashi because of its natural flavors.
(Note 2) Microwave method: You can also make the marinade by adding all the ingredients to a microwave-safe bowl and heating it for about 30 to 45 seconds, just until it starts to bubble.
(Note 3)Peeling eggs: To make peeling easier, try piercing the shell before boiling, chilling the eggs in ice water, gently cracking the shell to let water seep in, adding a splash of vinegar to the boiling water, or peeling them under water!
Serving SuggestionsAjitama is great on ramen, abura soba, or warm Japanese rice! You can also use it for onigiri, as a side dish, or in a salad with broccoli and shrimp for a Japanese-style Cobb salad.Storage InstructionPlace them in the marinade in an airtight container and store them in the fridge for up to 2 to 3 days.