Oolong (sometimes called Wu Long in China) is a very broad category and a favorite among connoisseurs and foodies for its wide range of flavors and complexities. Oolongs are partially oxidized, falling somewhere between green tea and black tea. They are made by plucking relatively mature, whole leaves and then partially oxidizing them depending on the specific style. Most oolongs range in oxidation from 10-80%. The less oxidized an oolong, the closer in flavor it will be to a green tea; the more oxidized an oolong, the closer in flavor it will be to a black (red) tea. Oolong making is a very precise, time-consuming process, with each step very closely monitored and labor intensive. Multiple stages are repeated to achieve the desired amount of bruising for each tea.
Originating in the Wu Yi Region of China, oolongs have become culturally important in both China and Taiwan. Some connoisseurs believe that although oolongs originated in China, it was Taiwan who perfected them. As a category, oolongs have the widest array of flavors and aromas - with various sub-categories. In China, the main categories of Wu Longs are Yan Cha (Cliff) teas, An Xi & Dan Cong (Phoenix) teas. In Taiwan, oolongs are categorized as Formosa teas.
Depending on the making, oolongs are known to have notes of honey, flowers, fruits, cream, vanilla, and citrus. The Chinese category of Yan Cha specifically, is known for its mineral, molten rock flavors, a stark contrast to most other oolongs.