Wash with warm water. According to the relevant public information, the sugar of yam can stick to the plate and can be easily cleaned by soaking in warm water for 10 minutes. Yam is the dried rhizome of Dioscorea opposita, a plant of Dioscorea, which is made by cutting off the root head, washing the soil, scraping off the skin with a bamboo knife, drying in the sun or drying in an oven.