Pickling and making mustard vegetables is an important event in Gungguan, Miaoli where unique and diverse pickled products known in every corner in Taiwan are produced. The ingredient of Fu Tsai comes from leaf mustard grown in Gungguan. It is pickled vegetable with salt. After drying in a cool place or under the sun, before it is completely dehydrated, it is put in a large container. Then the container is sealed for natural fermentation for about one month. No preservatives or artificial colors are added during production. Natural fermentation presents a unique flavor.