Finely chop the onions and put them in a heatproof container. Top with butter, cover, and microwave for 1 minute and 30 seconds. Let cool.
Put the panko in a bowl. Add milk and let it soak into the panko.
Add the ground pork, onion, salt, and pepper to the bowl from Step 2. Knead well until the mixture becomes sticky. Add the egg and mix well.
Divide the meat from Step 3 into two equal pieces. Remove air bubbles and shape into ovals.
Grease a heated frying pan. Add the meat from Step 4 and cook over high heat until browned. Flip and cook the other side the same way. Add the water, cover with the lid and cook over low heat.
You'll know the hamburger steaks are done when the juices are coming out of the meat and it looks plump and soft.
You can add nutmeg to taste
Find out how to prepare terikayi sauce from this Recipe ID: 1887403.
Hamburger Sauce Recipe ID: 1738994
Story Behind this Recipe
I often make hamburgers with tofu added, but this is another recipe I've been making for a long time. Italian hamburgers steaks: Recipe ID: 675809 Hamburger Steak Curry: Recipe ID: 2159098 These are good with teriyaki sauce or other flavors.
*Use lean meat rather than meat that has a lot of fat content. *For bento, shape the meat into smaller shapes before cooking. *If you're using a small onion, use half of it. *You can top the hamburgers with cheese if you want and then top them with sauce. These are also good with teriyaki sauce or shiso leaves + grated daikon radish topped with ponzu.