Put the cut sweet potato and purple potato into a pot and steam for about 15 minutes. When you touch them with chopsticks, you can turn off the fire. The purpose of steaming them is to keep their viscosity and taste firmer. It's important to take it out to cool immediately after steaming. It will be very slippery after cooling. Crush sweet potatoes and purple potatoes with a rolling pin or something like a rolling pin. Crushing is easy, effortless and requires crushing. Cassava flour (tapioca flour) was added to sweet potato paste and purple potato paste respectively, and the addition amount was about 15g, with more sweet potatoes and less purple potatoes.