Oca is a tuber prized for its brilliant colors, especially its cherry-red skin (although it can come in a variety of colors). Red-skinned varieties have an orange flesh, similar in color to a sweet potato. Oca is said to taste like potatoes that already have sour cream, with a slightly acidic flavor. Use them as you would other petite potatoes; they can be boiled, roasted, baked, mashed or fried. The tuber is also known as the New Zealand yam.