Beef with Broccoli in Oyster Sauce

Thais make this dish with pahk ka-nah, a sturdy, delectable cousin of broccoli that is longer on leaves and shorter on flowers. Its Cantonese name is gai-lan, and its leaves easily pass for collard greens, in color and texture though not in size. If pahk ka-nah is not handy, mai pen rai—never mind! Grab your favorite leafy green, be it spinach, Swiss chard (red or green), beet greens, rapini, Napa cabbage, or bok choy, or use broccoli, as I have here. All are good, all are good for you, and