Prepare the washed greens by cutting the leaves from the stems. Trim the stems as you might asparagus, peeling away the tougher skin and cut on the diagonal into 6 cm (2-inch) pieces.
Coarsely chop the greens and florets and set all aside.
Heat the oil in a wok or large sauté pan and add the garlic and ginger, then immediately add the greens.
Toss and stir for a few seconds to completely coat everything and distribute the ginger and garlic. Raise the heat and add the rice wine vinegar around the outside of the pan, pushing the greens into a pile in the centre.
Cover and steam for a couple of minutes then uncover and scoop the greens around the hot edges of the wok or pan.
Add salt, sugar, pepper and stir-fry another minute or so until tender. A splash of water or stock will help at this point if the greens are looking a little dry.
Serve. Best eaten right away.