1.Wash crabs. Gently pull away round hard shell at top.
2.With small sharp knife gently cut away the grey fibrous tissue. Rinse again to clean crab.
3.Chop off claws and big nippers. Crack these lightly with back of cleaver to break through the hard shell. This makes it easier to eat the crab meat. Chop down centre of crab to separate body into two halves. Then chop across each half three times, this gives six body sections of crab.
4.Remove seeds from red pepper, cut into very thin strips. Chop shallots into 2.5cm (1in) lengths. Peel ginger, cut into very thin slices, then cut each slice of ginger into very thin strips.
5.Combine oil and sesame oil in wok or pan, add prepared ginger, saute very gently for two minutes, add prepared crab, toss one minute. Add red pepper, water, sherry, soy sauce, crumbled stock cube and sugar, bring to boil, reduce heat, simmer covered for four minutes, remove lid. Add combined extra water and cornflour, toss for two minutes or until sauce is boiling and coats crab well. Add shallots, toss for one minute.