Bring a small saucepan of water to the boil, add livers and cook for 2 minutes and drain, cool and slice. Shell and de-vein prawns. Place shells and heads in a saucepan with 250 ml (8 fl oz/ 1 cup) water and simmer for 30 minutes. Stir in wine or sweet sherry, strain and reserve liquid.
In a wok, heat oil, add chilli and ginger and fry for 30 seconds, add livers and stir-fry for 3 - 4 minutes. Using a slotted spoon, remove from wok and drain on absorbent kitchen paper. Add prawns to wok and stir fry for 2 minutes then return liver, chilli and ginger to wok and cook for 2 minutes. Stir in reserved prawn liquid and bean paste and simmer for 5 minutes. Stir in the cornflour (cornstarch) mixture and bring to the boil, stirring.
CORNFLOUR MIXTURE: Measure spoons of cornflour into a bowl, then stir in twice the amount of water. Pour into a screw-top jar and keep in the refrigerator. Stir or shake jar before measuring out required amount.