Fingerling potato - Wikipedia, the free encyclopediaA fingerling potato is a small, finger-shaped type of potato which may be one of any number of heritage potato cultivars. Similar to heirloom tomatoes in the fashion they are cultivated and treated in cooking, fingerlings are varieties that naturally grow small and narrow. Fingerlings are fully mature when harvested, and are not to be confused with new potatoes. Popular fingerling potatoes include the yellow-skinned Russian Banana, the orange-skinned French, and the Purple Peruvian. Due to their size and greater expense compared to other potatoes, fingerlings are commonly either halved and roasted as a side dish or used in salads.
The bags I got at Costco had several varieties, including the purple ones.