Stir-Fried Chinese Lettuce, Garlic, and Black Beans

The Chinese love a vegetable not often seen in the United States. They call it lettuce; in America it might be labeled celtuce, stem lettuce, woh sun, or Chinese lettuce. In my local Asian market, it is labeled A-choy. With leafy greens sprouting from a long, thick stem, it looks like a little tree. The tops resemble romaine lettuce, which makes a fine substitute. The thick, tender stems have the texture of broccoli stems or kohlrabi, with a lettuce-like flavor. In America, the tops