These are simple spring cabbage hamburgers. The are extremely juicy and delicious! You could also use 1 whole onion if you omit the cabbage.
I received lots of spring cabbage, so I added them to hamburgers!
Make sure to drain out the water from the spring cabbage very well. Finely chop the onions and add them raw. When the hamburgers have finished cooking, it's fine if there's a lot of leftover water.
Enjoy Japanese food around the world.