Purple potato annual ring cake

Nowadays, it is difficult to find traces of purple potatoes in the market. If you want to eat them again, you can only wait until the autumn harvest season. This small cake was made in early May and has been stored for a long time. I put it on it today and invited everyone to taste it. At that time, the original flying cakes in the supermarket were out of stock, and I felt that the flavor of scallion oil was still not as good as the original flavor.