I do not own a wok, and regret the lack only when I cook pak choi. The stalks and, particularly, the leaves of pak choi disgorge a lot of water, which the high heat and large surface area of the wok help to evaporate. A large frying pan does not perform the job so well; a saucepan, hardly at all.
You strip off the leaves, and cut the stalks into fork-sized pieces. Heat the pan and the oil, and, before the oil starts smoking, throw in the stalks. They tenderise much more quickly than do those of, say, chard -- in about three to four minutes. Throw in the leaves, and give them a minute to wilt.
It's done. If you have water in your pan, drain the pak choi. It would be a shame to overcook it while waiting for the water to evaporate.