Firstly, a spicy curry paste is made. Various vegetables are simmered with stock and said curry paste, and the final touch is to blitz just-cooked white fish into flakes, then add it to the soup for essential fish flavour, texture and to thicken it up a bit. I used the cheapest white fish I could find for this, coley; alternatively, you could just drop chunks of white fish in to poach. The bai yor leaves go in last for a final simmer; they act like spinach and wilt down, adding a slightly bitter flavour to the dish. It's fine to leave out if you can't find it.
Sour Fish Curry
For the paste
5 red birds eye chillis
5 dried chillis
2 stalks of lemongrass, soft innards only
1 inch piece of galangal
2 tbsp tamarind paste
1 small onion
6 cloves of garlic
1 tsp sugar
1/2 tsp salt
Soften dried chillis in hot water. Deseed the chillis and blitz with the rest of the ingredients into a fine paste. You may need to add a little oil.
200gr white fish
A handful of green beans
A few leaves of Chinese cabbage
A few bai yor leaves (optional)
2 tbsp fish sauce
300mls fish or chicken stock
A handful of coriander, chopped
In a pan, add the curry paste and fry gently for a few minutes. Add the stock and the Chinese cabbage, then then green beans cut into inch long pieces. Simmer for a few minutes. Either add the fish in chunks or cook the fish separately and blitz into flakes, then add to the soup. Add the bai yor, fish sauce, then the prawns and cook until the prawns turn pink and take off the heat immediately. Serve with a wedge of lime and rice, if desired.