450 g (1 lb) fish fillets, such as mackerel, cod or haddock
30 ml (2 tbsp) plain flour
groundnut oil for frying
1 onion, roughly chopped
1 small garlic clove, crushed
4 cm (1 1/2 in) fresh root ginger, peeled and grated
1 - 2 fresh red chillies, seeded and sliced
1 cm (1/2 in) cube terasi, prepared
60 ml (4 tbsp) water juice of 1/2 lemon
15 ml (1 tbsp) brown sugar
30 ml (2 tbsp) dark soy sauce
salt roughly torn lettuce leaves, to serve