Put the mud crab in the freezer for 1 hour to send it to sleep. Once asleep, take it from the freezer and work quickly. Turn the crab upside down and make an incision with a sharp, heavy knife into the middle of the body, driving the knife down between the eyes. You can now pull the body out of the shell. Discard the tail, lungs and stomach sac. Wash the crab thoroughly under cold water to remove any mud, and scrub the shells with a clean sponge. Separate the claws and knuckles, and cut the body into 4–6 pieces. Using the back of a heavy knife, carefully crack the claws and knuckles. This makes it much easier to hoe into later.
Heat a wok over a medium–high heat, add the butter and bring it to bubbling point. Just as the butter starts to foam, add the garlic and ginger and cook, stirring continuously, for about 2 minutes until fragrant. Add the pepper and cook for 1 minute, then add the chicken stock, oyster sauce, sugar, kombu extract and salt. Bring to the boil and simmer until the sauce has reduced by one-third. Add the 3 cm (
Fill a large heavy-based saucepan or deepfryer one-third full with oil and heat to 180°C (350°F) or until a cube of bread dropped into the oil turns golden in 15 seconds. Dust the crabmeat pieces in potato starch and set aside. Gently lower the claws and knuckles into the hot oil. Be careful as the oil may spit. Fry for 2 minutes and then add the dusted meat pieces. Fry for another 2 minutes, then drain on paper towels.