1.In a large bowl, combine cabbage, carrot, green onion, ginger and garlic. Mix well. Gently toss fish through mixture.
2.Dip one sheet of rice paper in warm water, for about 30 seconds until just softened. Transfer to a clean tea towel on a flat surface. Place 1 tablespoon of mixture diagonally along the centre. Fold over sides. Roll up firmly to enclose filling. Repeat with remaining ingredients.
3.To make the dipping sauce; combine water, sugar and vinegar in a small saucepan. Stir over a high heat until sugar dissolves. Remove from heat and stir cucumber and red onion through. Add peanuts just before serving.
4.Heat oil in a medium saucepan on high until a cube of bread sizzles as soon as it is added. Cook rice paper rolls in batches for 3-4 minutes, until crisp. Drain on paper towel. Serve hot with dipping sauce.
If you have a thermometer, oil should be 180°C. Be sure to remove any random bones.