Seafood tempura

3 oysters , shucked but shells reserved

3 strips of white fish

1 lobster tail , peeled but shell reserved

oil , for deep frying

100 g plain flour

1 tsp cornflour

pinch of salt

cold soda water , according to consistency

1 tbsp dark soy sauce

4 spring onions , chopped

1 red chilli , finely chopped

1 tsp fish sauce

1 tsp fresh lime juice

1 tbsp mirin

1 tbsp light soy sauce

1 tsp peanuts , crushed

1 tsp coriander roots , chopped