If you want to get a sense of the vigorous, animated nature of stir-frying, the best place to start might be with physician and writer Buwei Yang Chao’s definition of ch’ao, the Chinese word for the technique. “Roughly speaking,” she writes in How to Cook and Eat in Chinese, the seminal 1945 cookbook she produced with her husband and daughter, “ch’ao may be defined as big-fire-shallow-fat-continual-stirring-quick-frying of cut-up material with wet seasoning. We shall call it ‘stir-fry’ or ‘stir’ for short.”
The main thrust of Chao’s definition is that stir‑frying employs high heat and constant motion to cook food so rapidly that proteins brown uniformly and vegetables lose their raw edge but retain vibrant color and fresh crunch. As soon as the food hits the wok, it’s repeatedly pushed, flipped, and swirled all over the vessel’s surface, which allows its moisture to evaporate quickly. When that happens, existing flavor compounds in the food become concentrated, and new, more savory compounds develop as the cooking surface gets hot enough to produce Maillard browning.