2. Sago in a blender.

3. Grind into fine powder.

4. Purple potatoes are put in a steamer and steamed.

5. Peel the steamed purple potatoes while they are still hot and add a spoonful of sugar.

6. Grind the purple potatoes into mashed potatoes while they are still hot and set aside.

7. Grind the fine rice flour and add a little bit of warm water.

8. Form a rice ball that is slightly softer than the dumpling dough and let it rise for 20 minutes. (Cover with plastic wrap)

9. Roll out the dough on a floured surface.

10. Wearing disposable gloves, roll the mashed purple potatoes into strips and place them on top of the rolled out sago dough.

11. Roll up from one end.

12. Roll one circle and cut off the excess.

13. Cut to your favorite length.

14. Into the steamer (cooked crystal cake is very sticky, the steam drawer must be smeared with oil)

15. steam, medium heat steam 15 minutes can be turned off the fire.