1. Sweet potato cake needs to be steamed for about 20 minutes.

2. Sweet potatoes have high edible value and are rich in vitamins, protein, starch and various minerals. The length of time to steam sweet potatoes depends on the discovery of the sweet potatoes. First, clean the prepared sweet potatoes, then boil the water in the pot and put the sweet potatoes on top. After about 20 minutes, you can poke the sweet potatoes with chopsticks. If they become very soft, Then it is ready to be cooked. If it is a larger sweet potato, it will take about half an hour to steam.