Ever since I bought Alicia Silverstone's The Kind Diet, I've been on the lookout for Bok Choy. She features it in quite a few recipes, and although I always looked for it, I could never find it in my local food shops.
I was quite happy when I found a small Japanese supermarket around. It actually features more of the processes junk food you can find in Japan, but in a small fridge I found it among some produce.
It has a lovely taste, a bit on the bitter side, but nothing as bitter as radicchio. My favorite version of it was in a salad with lots of tomatoes, carrots and a tahine based sauce. I recommend it!