Tom yum goong (Thai hot and sour shrimp soup)

Twist the heads off the shrimp into a stock pot; cut the shell along the back with pointy scissors, peel and add the shells to the pot, and remove the veins (the shrimp are butterflied in the process).

Add a little oil, and optionally finely chopped daikon and/or onion; sauté on medium-high, pressing the heads to release the shrimp fat.

When the bottom of the pot starts to brown, add water before it burns; bring to a boil and simmer 5 minutes.

Scoop out the shells and measure the stock, topping up with water to about four cups.

Cut the root end off the bottom half of the lemongrass, smash it with a knife or pestle, and cut into big chunks.

Twist and tear the makrut lime leaves to bruise them, removing large center ribs.

Partially thaw frozen galangal 10 to 15 minutes and slice it, putting the slices in a bowl at once.

Bring the stock to a boil and add the lemongrass, galangal, lime leaves and chilies with their seeds (optionally wrapped in cheesecloth to remove before serving).

Pound Thai chilies in a mortar and pestle.

Add oyster mushrooms and simmer with the herbs about five minutes.

Loosen the nam prik phao with some of the broth.

Season with fish sauce, then the nam prik phao; hold the sugar and lime juice for the end.

Bring back to a boil on high, add the shrimp for about 30 seconds, then turn off the heat and let residual heat finish them.

Add the lime juice off the heat; the soup should lead with sour. Taste, adding a little sugar only if the sourness is too sharp, or hot water if overall too strong.

Finish with chopped cilantro.