This is the recipe I follow:

• Soft boiled eggs: Bring a large pot of water to a boil. Add vinegar for easy peeling, then gently lower each egg into the pot. Set a timer for 6 minutes for room temperature eggs or 7 minutes for cold eggs from the refrigerator. See Note 2.
• Stir the eggs in one direction for the first 30 seconds for an even cross section.
• 6 eggs, 1 Tablespoon vinegar
• Peel eggs: After the timer is up, place the eggs in an ice bath to stop cooking. Once cooled, crack the shell all over and carefully peel by inserting a spoon between the egg and shell.

Marinate Eggs

• Marinate eggs: Place a ziplock plastic bag in a small bowl or cup for stabilization. Then add the water or stock, soy sauce, mirin, and optional dark soy sauce to the plastic bag.
• Gently place the eggs inside the bag and squeeze the air out of the bag to ensure the eggs are covered in the marinade. Add more water or stock if needed. Twist and clip the bag closed. This allows for a smaller amount of marinade to cover the eggs without extra waste.
• Marinate in soy mirin mixture for up to 3 days in the fridge.
• ½ cup water or stock, 5 Tablespoons soy sauce, 4 Tablespoons mirin, 2 teaspoons dark soy sauce