Yka Leaves® is the Koppert Cress brand name for an edible leaf. Yka Leaves have a strong sour taste, with a slightly sweet undertone. The leaves are deep purple in color and have a light pattern, which makes them very decorative. Yka Leaves pair well with lobster, scallop, or shellfish. But they also do well in vegetable dishes with 'earthy flavors' like beets, carrot, or tubers.