Lip-smacking, tangy, chewy, and exotic, these morsels go perfectly with drinks before dinner, and very well without drinks at any time. Boil 2 quarts of the water with the alum for 5 minutes, then remove from the heat and allow to cool. Boil the vinegar with the sugar and salt for a few minutes, or until the sugar is completely dissolved. Remove from the heat and cool. Boil the remaining 2 quarts water and drop in the pigs ears. Boil for 20 minutes. Remove the pigs ears and cut them into lengthwise slices 1/4 inch wide. After the sliced pigs ears have cooled, return them to the alum water to soak for 2 hours, then drain and rinse under cold water. Dry lightly. Place the pigs ears in a jar, pressing them down. Pour in enough cooled vinegar mixture to completely cover the contents of the jar. Refrigerate. NOTE: This can be eaten after 3 day and will keep for several weeks in the refrigerator. Yields 2 quarts From "The Classic Cuisine of Vietnam", Bach Ngo and Gloria Zimmerman, Barrons, 1979. ISBN 0-8120-5309-5