The rarest and most unusual type of tea, yellow tea has mysterious origins dating back hundreds of years. Its birth, like many tea types, was probably accidental, starting as green tea that was bundled while still warm. This 'yellowed' tea was found to have a more mellow flavor, without some of the grassy qualities associated with green tea, so the process was developed further.
Yellow tea is processed much like green tea, but after a shorter and lower temperature sha qing, the still-warm tea leaves are wrapped in bundles, which allows some slow oxidation and causes the leaves to turn slightly yellow. This process is called men huang - 'sealed yellowing'. This extra step is delicate and time consuming; as a result, very little yellow tea is produced in the world. Some teas sold as 'yellow tea' skip this step; but without men huang, it's really green tea. Because of this scarcity, true yellow tea is rarely seen outside of China.