oolong tea Partially fermented, Oolong tea is between black and green teas on the processing scale. This creates a delicious combination of the best aspects of both green and black teas while providing a flavor profile all its own. This is the preferred type of tea for many connossieurs. Under the name Wu long tea, this tea has become popular in recent years due to its reported "slimming effect". Demand for this tea has skyrocketed, limited supplies available.