1. Peel the purple sweet potato and cut it into large pieces. Steam it in a steamer. After 15 minutes of steaming, fork it with chopsticks. You can stop the fire easily
2. Put the purple sweet potato into the blender, add some warm boiled water into fine mud
3. Take the center as the origin to squeeze the condensed milk outward
4. Use a toothpick or a pointed bamboo stick to draw the word 'rice' on the purple potato soup