Cut any large prawns in half. In a bowl, mix prawns, pork,
chicken, grated carrot, water chestnuts, preserved vegetables,
garlic, spring onions, sugar, fish sauce and salt and pepper. Fill a bowl with warm water, then
dip sheets of rice paper in water one at a time. If using large sheets of rice
paper, fold in half then place about 2 tablespoons of filling on to
long end of rice paper, fold sides over to enclose filling and roll
up, then seal end with a little flour paste. The roll will be transparent,
hence the name 'crystal'. To serve, place some mint and
coriander in a piece of lettuce leaf with a crystal roll and wrap
into a near parcel, then dip roll into Spicy Fish Sauce before
eating.