Oolong teas hold the widest range of flavor and diversity. They are oxidized between 10-80%. They are a traditional tea of China and range between green and black tea. They are generally processed one of two ways by either rolling into curled leaves or pressed into ball-like forms. Oolong teas are the most complicated to produce and give way to a wide variety of flavors and forms. Taiwan is well known for its fine Oolongs.