Cut 100 g yellow onion(s) into wedges.
Once the kombu is rehydrated, place a saucepan on the stove and pour in the contents of the jug. Turn on the heat to a low setting and slowly bring to almost boiling (small bubbles will appear around the edge, but don't let it boil).
Remove the kombu, add 50 ml mirin, 1 tbsp light brown sugar, 1 tsp Chinese-style chicken bouillon powder and mix.
Add the onion to the pan and turn up the heat to medium, cook until the onion is softened.
Add 2 tbsp soy sauce and stir to distribute it, then lay the katsu over the top.
Separate 3 medium egg(s) into two bowls and whisk the whites.
Pour the egg whites around the pan (don't add the yolks yet).
Place a lid on the pan and allow the eggs to steam for about 1 minute.
Lightly whisk the egg yolks and then pour them around the pan.
Place the lid back on and turn off the heat. Allow the egg to cook in the residual heat until it's cooked to your preferred firmness.
Dish up 2 portions cooked Japanese short-grain rice into serving bowls and place the katsu and egg mixture on top.
Garnish with Japanese wild parsley (mitsuba) "mitsuba" (optional).
Enjoy!