Makes 16 rolls. Keep the filling dry or the rolls will split: salt the shredded cabbage, leave it 10 minutes and squeeze it out, drain the bean sprouts and bamboo shoots, and pat the seafood dry.
Chop the seafood small, roughly the size of a bean sprout. These are only in the oil for 3 to 4 minutes, so anything in large pieces will still be cold in the middle when the wrapper is ready.
Fry four or five at a time at 180C and let the oil come back up between batches. Crowding the pan drops the temperature, and cool oil is absorbed rather than crisped. Drain on a wire rack, not on kitchen paper.
To freeze, freeze them assembled but raw on a lined tray, then bag them and fry straight from frozen with an extra minute or two. Do not thaw them first. If the prawns were sold frozen and thawed, cook them before they go into the filling rather than refreezing them raw.