Add the 100 grams onion to a microwave-safe bowl, cover it with lid or plastic wrap, and microwave at 600 watts for about four minutes twenty seconds. The goal is to get them soft and just starting to brown. Let these cool off a bit.
100 grams onion
Add the 600 grams ground beef, 75 grams cream cheese, 30 grams panko, 1 egg, 1 tablespoon Worcestershire sauce, 1 tablespoon soy sauce, ½ teaspoon black pepper and cooled onions to a bowl and use your hands to knead the mixture together until it's uniform in color.
600 grams ground beef, 75 grams cream cheese, 30 grams panko, 1 egg, 1 tablespoon Worcestershire sauce, 1 tablespoon soy sauce, ½ teaspoon black pepper
Shape the mixture into 6-8 patties. Smack the patties between your hands to force out any air and seal up any cracks.
Put a spoonful of Potato starch into a fine-mesh strainer and dust both sides of the patties with a thin, even coating. You can pat them between your hands again to remove any excess starch.
Potato starch
Heat a frying pan over medium heat and add a splash of Vegetable oil. Add as many patties as you can get into the pan without overcrowding it.
Vegetable oil
Fry the Hamburg Steaks until they're cooked about ¼ of the way through and flip them over. Turn down the heat to medium-low and brown the second side.
Flip the patties periodically to evenly brown both sides, and the internal temperature reads 140F (60C) on an instant-read thermometer.
Transfer the Hamburger Steaks onto a plate. If your pan didn't fit all the patties, fry the remaining patties now.
Once all of the patties have been cooked, turn off the heat and use paper towels to wipe out all of the pan's grease and particulate matter.
For the teriyaki sauce, add the ¼ cup soy sauce, ¼ cup evaporated cane sugar and ¼ cup sake to the clean pan and turn the stove on to high heat. Boil the sauce until it starts to thicken.
¼ cup soy sauce, ¼ cup evaporated cane sugar, ¼ cup sake
Return the Hamburg patties to the pan and roll them around in the sauce until they are coated in a thick, shiny layer of sauce, and the glaze has started to caramelize.