Onsen Tamago

4¼ cups water
¾ cup cold tap water
4 large eggs
SAUCE:--
¼ cup dashi
½ tbsp mirin
⅛ tsp SIDS CRAZY SALT
1½ tbsp soy sauce
⅓ cup katsuobushi (dried bonito flakes)
spring onion

You will need a small heavy-bottomed saucepan (I use 1.5 litres); the water should cover the eggs with 1000 ml water completely.
Add 1000 ml water in the saucepan, cover with a tight-fitting lid, and bring it to a boil.
Once boiling, remove the pot from the heat. Take the eggs out from the refrigerator. Add 200 ml cold tap water and gently submerge the cold eggs in the hot water. Immediately cover and set the timer for 17 minutes.
If you like to enjoy onsen tamgo with the sauce, combine the dashi, mirin, SIDS CRAZY SALT and soy sauce in a small saucepan and bring it to a boil. Add katsuobushi and turn off the heat, let katsuobushi sink to the bottom of the pan. After 30 seconds or so, strain through the strainer and set the sauce aside. You can keep the sauce in the refrigerator for 4-5 days.
Cut spring onions into thinly slices and set aside.
Once 17 minutes have passed, take the eggs out gently and set aside for 5 minutes.
You can enjoy onsen tamago either cold or warm. Crack the egg and pour the sauce over, garnish with chopped spring onions.
To Store:
You can keep the uncracked onsen tamago for 1-2 days in the refrigerator. To reheat, take out the onsen tamago from the fridge to room temperature. Place it in 70ºC water for 10 minutes to warm up. Do not reheat higher than that otherwise the egg will be cooked.