LIKE WATER FOR HOT CHOCOLATE By Laura Esquivel (Doubleday, $135) DO you know how to castrate a chicken? Indeed, did you know that castration is a prerequisite for the preparation of capons? Apparently the best way to perform this culinary operation is to make an incision over the chicken's testicles, stick a finger in to get hold of them, and then pull them out. It is far beyond the reviewer's customary duties to put this method to the test but I see no reason to distrust Ms Esquivel who is bursting with recipes and tips about how to perform various household chores. According to her publishers this best-selling Mexican author has produced a ''unique culinary romance''. I have to admit that the culinary romance is a literary genre with which I am totally unfamiliar but that is not to say that it won't take off. After all, science fiction was considered pioneering when H. G. Wells started messing about with time machines. Indeed if culinary romance is the coming thing in literature, Laura Esquivel has proved herself to be a worthy pioneer. She has a list of characters almost as rich as some of her recipes. Take, for example, her sister's wedding cake recipe. It required 17 eggs, 175 grams of refined granulated sugar matched by a ''mere'' 300 grams of cake flour ''sifted three times''. I quite like Mexican food every now and again but have to say that I am quite defeated by some of Ms Esquivel's recipes. Chocolate and Three Day King's Bread requires prior roasting of the chocolate beans, which must be done in a metal pan rather than anearthenware griddle. It all sounds too much like hard work and is certainly not recommended for the weight conscious. This particular concoction has a total of six pounds of different chocolate beans and four to six pounds of sugar. And what of the rich characters? The richest is Tita, who suffers under the family curse of having to remain a spinster faithfully serving her mother until her death but, of course, does not. Then there's her sister Rosaura who steals her boyfriend and becomes incredibly fat and smelly (and gets her just comeuppance for so doing) and the other sister Gertudis who goes storming out of the house naked, serves a brief spell in a brothel and becomes an officer in Mexico's revolutionary army. I hope you're getting some of the flavour of the book by now. It is, to put it mildly, not totally wedded to realism. However, Ms Esquivel has a knack of verging on going over the top but desisting at the last minute. She has a wonderful sense of the absurd and a gentle sense of humour which propels the book along making it hard to put down. In the best tradition of the English pantomime, I found myself wanting to boo the bad characters and urge on the goodies. Tita's mother, who makes an eloquent case for retrospective abortion, has few redeeming qualities, but her evil is not overdone. While Tita the heroine is sympathetic she is not without her faults, a scheming side to her nature being high on the list of negatives. It is rare to come across a book as unusual as Like Water for Hot Chocolate . I can well understand why it shot to the top of the Mexican best-seller list. A fine translation by Carol and Thomas Christensen makes it highly accessible to the English-language reader and so there is no reason why Ms Esquivel will not achieve equal success elsewhere. Incidentally, do you know how to keep eggs fresh for months? It's simple, according to Ms Esquivel. Place them in a cask containing crumbled sheep fodder, allow to cool and then cover completely. I'm sure the average person in Hongkong will find this advice extremely useful. I'm just dashing out for a supply of sheep fodder. It's so much better than spending time queuing at Park'N Shop.