Yam is rich in carbohydrates, that is, sugar. Starch tends to turn into cooked food in the process of stewing. If yam is stewed for too long, it will cause serious changes in starch, which is not conducive to the absorption of nutrients. On the contrary, if yam is stewed for too short a time, the nutrients in yam will not change well, which is not conducive to human absorption. In the process of stewing yam, we must master the heat, and the general time is about 20 minutes. If the variety of yam is different, or different from other ingredients of yam stew, the stew time is about 20 minutes, which can float up and down. It takes less time to stir-fry yam, and it takes about 5-8 minutes to stir-fry yam in oil, so that yam is cooked.