That's tough. Some stuff is pretty frost tolerant. Crinkly spinaches and kale.
I just brought in the Toy Choy. Actually pretty good. But didn't get a lot. The plants are really small compared to real bok choy.
Just tried bok choy for the first time last month. Damn tasty! I would like to find some and try to grow it, heck Im not even sure you can grow it here.