Wash the
crabs well, scrubbing away any mossy patches on the shell.
Remove hard
top shell, stomach bag and fibrous tissue and with a cleaver chop each
crab into 4 pieces or 6 pieces if they are large.
Heat a wok,
add oil and when oil is very hot, fry the crab pieces until they change
color, turning them so they cook on all sides.
Remove to a
plate.
Turn heat to
low and fry the ginger, garlic and red chilies, stirring constantly,
until they are cooked but not brown.
Add the
sauces, sugar, soy sauce and salt, bring to the boil, then return crabs
to the wok and allow to simmer in the sauce for 3 minutes, adding very
little water if sauce reduces too much.