For the Tonkatsu:

1. Cut the pork into 4 pieces about 2cm thick and 5cm wide each (tenderloin is easiest for this)
2. With a rolling pin, tenderise the pork (by whacking it) and removing any excess fat
3. Season with salt and pepper to taste and leave to cool in fridge for 5 minutes
4. Meanwhile beat the eggs with a tablespoon of water
5. Place the flour and breadcrumbs in separate containers
6. With each piece of pork, dip first in flour (just a thin coating is needed), then in the egg and lastly in the breadcrumbs.
7. Deep fry in hot oil, turning several times until golden.
8. Cut each piece of pork into slices about 2cm wide

For the rest of the topping:

1. Cook the rice
2. Slice the onions in half and then into thin slices
3. Mix the dashi, mirin, shoyu, sake and sugar in a large saucepan
4. Bring to the boil, add the onions and simmer for 3 minutes
5. Add the pork cutlets and simmer for a further 1 minute
6. Carefully add the beaten egg onto each cutlet in equal amounts
7. Put the rice into 4 separate bowls when the eggs are just cooked with a slotted spoon scoop out the pork cutlets with the onion and egg and place together on top of the rice with a couple of tablespoons of broth