Prick the pork pieces all over with a sharp skewer.
Brine the pork pieces in a mix of 1 tbsp of sugar 1 tbsp salt, both dissolved into a container of water. Brine for at least 1/2 an hour on a kitchen bench and up to 2 hours in the fridge.
Prepare the stock by adding the sugar, soy sauce and mirin to the dashi or chicken stock. Keep warm in a saucepan.
Line up a flat plate, two bowls large enough to hold the pork pieces, and a fourth plate for the coated pork pieces: transfer the flour to the first plate; whisk the egg in the second bowl; and the breadcrumbs in the third dish.
Press a pork piece into the flour, one side then the first, ensuring it’s completely covered in flour.
Dip the flour-dusted pork piece into the egg wash.
Press the pork piece into the Panko breadcrumb mix, one side then the other, ensuring its completely covered in crumbs.
Move the pork piece to the empty plate, then repeat with the other pork piece.
Heat a saucepan with the oil to fry the pork. You want a stable 175°C (350°F) and carefully place the fillets in the pan. They should be fully cooked and golden brown within 3-4 minutes.
Place the Japanese rice in your serving bowls, ready to plate up the final dish.
Place 125 ml of stock in a saucepan that has the same top diameter as your serving bowls (so the final pork and egg fits in the bowl). Heat the stock until boiling.
Crack a single egg into a dish and whisk. Or if you're good with measuring, do all four eggs at once.
Chop each pork piece into 1.5 to 2cm slices and add one entire sliced pork piece to the pan. Drizzle the whisked egg over the pan, mainly around the pork slices. Cook for 30 seconds.
Whisk and add the next egg to the pan and some sliced spring onions
Place a lid on the pan for 30 seconds.
Remove the lid. At this stage you should be able to move the egg and pork layer as a whole piece. If not, cook for a little longer.
When the dish is ready – note that there will still be some liquid in the pan – place the pan over the rice dish and starting at the edge closest to you, slide the egg and pork on top of the serving dish. Garnish with a little green spring onions.
Repeat the process with the second dish.