To humanely kill the mud crab, place them in the freezer for 30-40 minutes until you see no movement at all, if they do twitch at all, put them back in the freezer until fully asleep, then immediately transfer from freezer to cooker and plunge them quickly into a large pot of boiling water. This is the most stress-free way. Never put them into simmering water; it must be boiling, this method is the most cruel-free manner.
2 fresh mud crabs*
2-3 blue swimmer crabs*, cooked
1/3 cup (80ml) olive oil
4 garlic cloves, finely sliced
1-2 long red chillies, finely sliced
2 spring onions, finely sliced
2 tbsp rice wine vinegar
2 tbsp tamarind concentrate*
1 tbsp Thai fish sauce
1 tbsp light soy sauce
1 tbsp chilli garlic sauce*
2-3cm piece galangal*, peeled, grated
Handful pickled green chillies or banana peppers
Handful fresh coriander leaves, roughly chopped
Place the mud crab in the freezer for 30-40 minutes until asleep, then plunge quickly into a large pot of heavily salted boiling water ~ see above note on the best and most humane way to cook mud crabs . You may need two large pots.
Cook mud crabs for 20-25 minutes, then plunge them into a large bowl of iced water. Remove the claws and legs, and crack them gently. Set aside. Remove shell from the body of the crab, then extract the crab meat, placing it in a bowl. Extract the crab meat from the cooked blue swimmer crabs in the same way.
Heat the olive oil in a wok over medium heat. When oil is hot, add the garlic and cook for 5 minutes before adding half the sliced chillies and half the sliced spring onions. Cook for a further 2-3 minutes.
Add the red wine vinegar, tamarind concentrate, Thai fish sauce, soy sauce, chilli garlic sauce, 1 cup (250ml) water and grated galangal. Simmer along with the garlic and spring onion for a further 2 minutes to infuse flavours before adding the loose crab meat and the crab claws/legs. Cook for a further 6-8 minutes, tossing often.
Transfer to a large serving dish and scatter with remaining thinly sliced red chilli and spring onion, and the pickled green chillies or banana chilli, and chopped coriander.
* Mud and blue swimmer crabs are from fishmongers. Tamarind concentrate and chilli garlic sauce are from Asian food shops. Galangal is from greengrocers and Asian food shops.