To CookIn a pot, bring the 1L of water to a rolling boil. At this point, remove the pot from the heat and in a heavy bottom saucepan, cover, and bring it to a boil.Once boiling, remove the pot from the heat. Remove the eggs from the refrigerator and set aside while you pour in the tap water to slightly cool the boiling water. Gently place the eggs in to the water and allow to slowly cook for approximately 13 mins while kept covered.While the eggs cook, combine the dashi, mirin, and soy sauce in a small saucepan and bring it to a boil. When the sauce begins to boil, add in the katsuobushi and remove the saucepan from the heat. Allow for the katsuobushi to sink in to the sauce before putting it through a strainer and setting it aside. Cut spring onions into thin slices and set aside.When the eggs have cooked, remove them and allow them to cool for approximately 5 mins.To plate, crack the egg open in to a small bowl and pour the sauce over; garnish with chopped scallion and serve!