Bean curd, dau fu, is as important in the Hakka branch of the Cantonese kitchen as it is to the Cantonese themselves. Stuffing hollowed-out cakes of bean curd is a hallmark of the Hakka, and a delicious concept it is. Always use fresh cakes of bean curd. It should be purchased fresh and stored in a sealed container of water, refrigerated. It will remain fresh for 10 days if the water is changed daily.