Is the water boiled with iron bar yam sour? Is it smoked by sulfur? Pretty scary. I bought yam slices from the drugstore and ate a lot.

Iron-stick yam is a precious Chinese herbal medicine, so it is called iron-stick yam because its epidermis contains rust color. Highly praised by doctors of all ages. As a traditional Chinese medicine, it can be made into various pills, such as Liuwei Dihuang Pill. As an edible vegetable, it is delicate, tender and has a unique flavor. Such as  yam and jujube paste yam. Because of the low water content and rich yam polysaccharide, the juice is thick, dry and sweet after cooking, and it feels "sweet on the face" when eaten with skin. So it must not be sour.