Cut orange-fleshed sweet potatoes (often mislabeled “yams”) into ½-in.-thick sticks and boil in water until tender-crisp, about 5 minutes. Drain and pat dry. Heat 2 to 3 in. vegetable oil in a large saucepan until oil registers 350° on a deep-fry thermometer. Fry in batches until golden and crisp, about 4 minutes.