Make several holes in the pork with a bamboo skewer, and put into a pan with the ☆ ingredients. If the pork is thick or if you're using a block that's larger than 300 g, cut into smaller pieces.
Add the sake and enough water to cover the pork pieces plus a bit more. Cover with a lid and turn the heat on to high. Bring to a boil, lower the heat and simmer for 10 minutes.
Turn the heat off, and leave the pork to cool naturally in the pan. It will cook through in residual heat. See the hints.
Make the sauce. Combine the ingredients in a heatproof bowl, and microwave until boiling.
Make "white hair" leek. Cut the white part of a Japanese leek in half and take out the core.
Shred very finely. Soak in cold water until the shredded pieces curl up.
If using an onion instead: soaked raw onion is delicious, but you can also cook in the sauce.
Slice the cooled pork. Top with the "white hair" leek, and serve with the sauce and Japanese mustard on the side.
The pork needs to be cooked thoroughly. Make sure it's cooked through by slicing through the center. See the hints.
The pork in this recipe doesn't keep as well as salty-flavored pork. If we don't finish it all the same day, I store it in the refrigerator (since we live in a warm climate).
If you like pork with lots of fat, a pork round may be too tough. Please try this recipe with different cuts.
Story Behind this Recipe
This is a recipe I've been making for a long time. It's a firm family favorite.
If you want to make a lot, cut the pork up into 200 to 300 g pieces and cook them all at once. If you're worried that a piece of pork didn't cook through properly, cut it in the middle after you're done. If it looks raw, heat through again. It won't affect the flavor.