Keep the pork in the marinade (oyster sauce, soy sauce, sugar, Japanese sake, ginger, garlic, miso) overnight.
Put the marinated pork into the pan. Pour in all the broth, too.
Add water and start heating the pan.
Put some vegetables in for flavour.
Onions, carrots and green onions.
After the broth starts boiling, add vinegar.
Vinegar magically helps the pork become tender and melty.
For a lid, I usually use aluminum foil with a crosscut in the middle.
Keep this boiling at a low temperature for about 2 hours.
If the broth gets low, simply add water or sake.
After about 2 hours, when the pork is soft or the fat is almost jelly-like, chashu is ready.
Keep the whole pan in the fridge overnight.
In the cold season, we can just keep the pan on the kitchen table.
When it cools, we can see a thick layer of pork fat on the surface of the broth.
The pork has lost its fatty part and has become wonderfully healthy food.
Scoop the lard off the top and keep it in some bag or container.
This lard will do a great job when added to the ramen soup.
Pull the pork out of the pan.
Filter out the vegetable remains.
And this process is extra, but my favorite part of Chashu cooking is to make brown boiled eggs in the broth.
Put the boiled eggs in the chashu broth.
Heat the broth to a boil, turn off the heat, and keep the eggs in it for 4~5 hours in the broth.
Bring the broth to a boil and keep boiling it until it gets more viscous. This thickened sauce is great to pour on the chashu pork.