I've tried several different recipes for Oyakodon, and this is my hack done to my personal taste.
I believe when they do this dish in Japan, they actually use a specific pan for it.
I've just used a regular frying pan for mine.
The first time I did this I pre-prepared all of my ingredients, but there really is enough time to chop and mix as you go with this one.
1. Slice up your onion - I like a varying degree of thickness in mine.
2. Get them going in your pan on a light to medium heat. Those onions are going to be there for a while so make sure they're not burning.
3. Slice your chicken into strips and place on top of the onions. Those onions are roasting slowly and should eventually caramelise. Don't stir anything - just let it be.
4. In the meantime mix your wet ingredients together (mirin, sugar, soy sauce and dashi). Add that to the pan, and hopefully it covers the chicken. We don't want to give anyone food poisoning!
5. Let everything simmer (still no stirring) and wait for the mixture to reduce and let the chicken cook.
6. Once the broth has reduced by at least half, lightly beat your eggs together (doesn't have to be completely mixed) and add to the pan.
7. Once your egg has set, stick some rice in the bottom of your don (bowl), and serve your oyako on top - preferably in one piece.
I love this dish almost as much as Gyudon - especially the yummy layer of caramelised onions between the rice and the protein!