Learn how to grow your own Oca with this video tutorial from Quickcrop with expert organic vegetable grower Klaus Laitenberger. Oca is a root vegetable that is not as popular as other root veg. perennial herbaceous plant that overwinters as underground stem tubers.The plant was brought into cultivation in the central and southern Andes for its tubers, which are used as a root vegetable. Oca was introduced to Europe in 1830 as a competitor to and substitute for the potato. Oca tubers are full of nutrients and have a nutty, slightly citrus flavour.