To Prep
Place water, Japanese soy sauce, mirin and sugar in a saucepan. Bring to the boil over medium-high heat.
Once boiling, remove from heat and add in bonito flakes. Leave for 20 mins, then strain through a sieve. Alternatively, if you can’t find bonito flakes in your local supermarket, substitute with 1 tsp of dashi powder instead.
To Cook
Crack 2 eggs in a bowl, then whisk. Repeat with 2 remaining eggs in a separate bowl.
In a small pot or pan, heat half dashi over medium-high heat. Add half the chicken and mushroom.
Once chicken is cooked, pour over one bowl of whisked eggs. Sprinkle with half of the spring onions, then cover with a lid.
Once egg is almost cooked, fill a bowl with rice, then transfer the egg, chicken and mushroom mixture onto the rice.
Repeat with remaining ingredients.
Serve.