Make the simmering sauce. Put the sake and mirin in a pan, and bring to a boil. Cook until the alcohol has evaporated, add the sugar and soy sauce, and the sauce is done.
Put a generous amount of oil into a frying pan, and shallow fry the pork belly block.
Put the shallow fried pork belly block and all the parboiling ingredients into a pressure cooker and heat. When it comes to a boil, skim off the scum, lock on the lid and cook under pressure for 20 minutes.
After 20 minutes, turn the heat off and leave until the pressure comes down naturally, and to continue to cook the pork with residual heat.
When the pressure has come down and the cooker has cooled down, take the meat out and rinse it quickly. Cut into 5 pieces.
Wash out the pressure cooker. Add back the pork belly, plus peeled and sliced daikon radish as well as the simmering sauce from Step 1. Heat the cooker to bring it up to pressure, and cook under pressure for 15 minutes.
De-pressurize the cooker and open the lid. Push the daikon radish to the side, add the boiled eggs and place a piece of paper towel on top of the contents of the cooker to act as a drop lid (otoshibuta).
Simmer to reduce for about 10 minutes, while pouring the sauce over the meat occasionally.
Serve on a plate with boiled spinach. Spoon over some of the sauce with Japanese mustard on the side.
Story Behind this Recipe
I wanted to have some delicious simmered pork belly, so I made this.
If you stir fry the pork in plenty of oil, the fat will come off easier. I also have a blog post about this recipe (Japanese): http://ameblo.jp/cooking-s-papa/entry-11645133507.html