Korean Yuja cha (yuza tea) is a traditional Korean tea made with citrus and honey. Yuja tea's main ingredient is the yuja fruit, a citrus fruit that ranges from yellowish-green in color (like similar a lemon) to bright orange; the ripest, best fruit will be orange in color. The taste somewhat resembles a tart grapefruit, although you should be able to detect traces of the fruit's mandarin orange ancestry as well. Korean yuja cha is very easy to make at home if you can find fresh citron or yuzu. If you cannot find fresh yuja, you can use yuja chung (citron tea marmalade), found at many Asian groceries and almost all Korean markets.
Yuza tea is recently enjoying a resurgence, and it's quite tasty and thirst-quenching.