Oksusu-cha (옥수수차) or corn tea is a korean tea made from corn. while oksusu-suyeom-cha (옥수수수염차) or corn silk tea refers to the tea made from corn silk, oksusu-cha can be made from corn kernels, corn silk, or a combination of both. the caffeine-free infusion is a popular hot drink in winter. along with bori-cha (barley tea), oksusu-cha is one of the free grain teas served in many restaurants in place of water.in gangwon province, the tea is called gangnaengi-cha (강냉이차)—gangnaengi is a gangwon dialect for "corn"—and is consumed throughout late autumn and winter in most households.

Source: Wikipedia