4 (about 700gm each) raw blue swimmer crabs, cleaned and halved lengthways 750 ml lager2 tbsp oyster sauce¼ tsp sesame oil1clove of garlic, chopped2 tbspginger, cut into julienne4green onions, cut into 5cm lengths2stalks of lemongrass, white parts only, bruisedTo serve:thinly sliced long red chilli, baby coriander leaves, thinly sliced green onions and steamed jasmine rice
Place crab halves in a large bowl, then add 60 ml beer, oyster sauce, sesame oil, garlic and 1 tbsp ginger, cover and refrigerate for 15 minutes.
Place remaining beer and ginger, green onions and lemongrass in the base of a wok. Place crab pieces and marinade in a heatproof shallow dish in a bamboo steamer over wok, bring beer mixture to the boil, then steam for 15 minutes or until crab is just cooked, adding boiling water to wok if necessary.
Transfer crab and cooking liquid to a large plate or bowl, scatter with chilli, coriander and green onions and serve immediately, with steamed rice passed separately.