Drain and reserve 1 cup pasta cooking water. Heat a large skillet over medium-high heat. Add olive oil, garlic and bok choy, and sauté until greens wilt and release their liquid, 4–5 minutes.

There are two points to look out for when stir-frying green bok choy. One is not to add the stem and leaves to the pan at the same time since they cook differently. Two is to use water wisely.