With pak choi (aka chinese cabbage, bok choi) you get two vegetables in one. Take the bottom and you have a slightly crunchy whitish vegetable, not unlike celery only much less offensive. Take the top and you have a robust green leafy vegetable (somewhere between cabbage and spinach) with bit of horseradish zing. Yum. I stir-fried mine with garlic and ginger and noodles and stuff. NB If you add the chopped stalks first, then the leaves just a couple of minutes from the end, then that works best.
There apparently over 20 varieties of pak choi although you pretty much only see the one type here in the UK. It’s also, like all cruciferous vegetables, obscenely good for you: lots of vitamins, folic acid, calcium and iron. And it is related not just to things you might expect like cabbage, but also to both mustard and turnips.
So there you go.