Put the chicken stock in a saucepan with the sliced ginger, spring onions and peppercorns. Bring to the boil and cook for 20 minutes so the flavours infuse.
Stand the corn on the cobs end-up on a board and slice away the kernels with a large sharp knife. Add the sweetcorn to the stock and simmer for 5 minutes.
Check over the crabmeat for any little pieces of shell, keeping the meat in the largest pieces possible.
Mix the cornflour with a little cold water to form a smooth paste, stir it into the soup and simmer for 2 minutes.
Stir in the crabmeat, chopped ginger, shredded spring onions, soy sauce and rice wine. Season with salt and pepper to taste. Simmer for 1 minute.
Give the soup a good stir, remove the spoon and slowly trickle in the beaten egg white so that it forms long, thin strands in the soup. Simmer for about 30 seconds and then serve at once.
