Thanks for the tip on refrigerating the korokke before frying!
I love potato croquettes and I usually eat it plain. So having beef in it is new to me and kinda made me wonder if it would be good. Conclusion: Yes! It is! I love the fact that it has a crunchy texture on the outside but it's soft in the inside. It's so filling too! Had this with the tonkatsu sauce and shredded cabbage which I stir fried for a minute. Thanks for posting this, Daydream!