Instructions

1. Make the dashi: Place the mushrooms and kombu in a medium heatproof bowl. Bring 2 cups of water to a boil in a large saucepan, and then let it stand off the heat for a minute or two (you don't want actual boiling water on kombu). Pour the hot water over the mushrooms and kombu, cover, and let steep while you cook the eggs.
2. Cook the eggs: Fill the same saucepan halfway with water and bring to a boil over medium heat. Gently lower the room-temperature eggs into the water and cook for exactly 7 minutes. Have a bowl filled with ice water nearby. When 7 minutes are up, immediately transfer the eggs into the ice water with a slotted spoon. Leave eggs in water to chill.
3. Peel the eggs: When the eggs are cool, peel them. Cassandra likes to use a spoon, turning it upside down and working the tip of it underneath the shell to separate the egg from the membrane. Place the peeled eggs in a 3-cup Mason jar.
4. Soak the eggs: Strain the dashi through a fine-mesh strainer into a measuring cup. Pour the dashi over the eggs — it should come to about 3/4 of the way up the jar. Top off with the soy sauce or tamari (you might not use it all). Seal the jar and refrigerate overnight.
5. Serve the eggs: When ready to serve, remove the eggs from the liquid and slice in half lengthwise. Place egg halves on top of ramen or other soups, in noodle or grain bowls, or on top of savory oatmeal or rice congee. They are also delicious when served with a few drops of sesame oil sprinkled on top.
6. Shortcut for bringing eggs to room temperature: If you've forgotten to bring the eggs to room temperature, warm them up a little by placing them in a bowl of hot tap water for about 5 minutes.
7. Storage: The eggs will last in the refrigerator for up to 1 week.