Add the butter and onion into a heat-resistant dish, cover with plastic wrap, and place in the CENTER of the oven  (Do not place in the Baking tray).

Select MANUAL COOK, MICROWAVE 600W and press ENTER.

2 minutes - 2 minutes 30 second, press START.

After cooking, remove excess moisture and chill.

Put water in the water tank.

Soak the panko bread crumbs in milk.

Knead the meat in a bowl with the salt before combining the onion butter mixture from step 2, the bread crumbs from step 4, and all ingredients of beaten egg, pepper and nutmeg.

Coat your hands with some Vegetable Oil and divide the meat equally into four pieces.
Gently pat the meat to help excess air escape leave and form round, flat patties that are about 9cm in diameter.
Line the baking tray with aluminium foil, lightly coat with vegetable oil, place the meat on the tray and press down in the CENTER of the meat.

<Important Point>

The reason why you gently pat the meat to remove excess air is because this helps prevent the meat from cracking while cooking. 
The reason why the recipe says to press down in the CENTER of the meat is because the CENTER expands when cooking.
It is recommended that the meat be about 1.5cm thick.

Select AUTO SENSOR COOK, NO FROZEN INGREDIENTS, BAKE and press START.

When cooking manually: 
WATER OVEN 2 / 1 tray/NO PREHEAT/about 24 minutes at 250°C.