Chop corned beef into 1 cm cubes. Place in a bowl.

Combine Worcestershire sauce and mustard and pour over corned beef. Mix to distribute evenly.

Peel and cut the onion into thin slices. Halve the slices.

Cut the potatoes into 1 cm cubes (leave the skins on).

Simmer potatoes in a pan of slightly salted boiling water for 5 minutes.

Drain the potatoes in a colander and then cover with a clean tea cloth to absorb the steam.

Heat 2 tablespoons of the oil in the frying pan and, when it's smoking hot, add the sliced onions and toss them around in the oil to brown for about 3 minutes altogether, keeping the heat high, as they need to be very well browned at the edges.

Push the onions to the edge of the pan and, still keeping the heat very high, add the potatoes and toss these around, too, because they also need to be quite brown. Add a little more oil here if necessary. Now add some seasoning, then, using a pan slice, keep turning the potatoes and onions over to hit the heat.

After about 6 minutes, add the beef and continue to toss everything around to allow the beef to heat through (about 3 minutes).

Turn the heat down to its lowest setting and, in the smaller frying pan, fry the eggs in the remaining oil.

Serve the hash divided between the two warm plates with an egg on top of each. Have plenty of tomato ketchup on the table.