RESTAURATEUR Johnny Yeo's culinary pride and joy is a nut. Not any old peanut, mind you, but a specially-imported Indonesian black nut which is scrubbed clean and soaked in water for three days before the meat is delicately extracted. Only then can the dish preparation begin for buah kauluak, one of the many Peranakan-style specialities at Yeo's homely Nonya and Baba restaurant in a suburb of Singapore. It helps to know a little bit of Peranakan history, not to mention the strange-sounding lexicon, to appreciate the food fully. Peranakans are a race of people who emerged from marriages between wandering Chinese sailors, who put down anchor in Singapore, and local Malay lasses. The merger of the two cultures led to a hybrid cuisine, which carries elements of southern Chinese fare, combined with the spicier, heavier, food preferred by the Malays. A whole sub-culture emerged with its own terminology: the men were known as babas, the women as nonyas, or bibiks, as they progressed towards matronly middle age. Peranakans had their own style of dress, their own dialect, a mixture of Chinese dialect and Malay, and their own district in Singapore. But despite the early-century richness of the culture, it had been dying a slow death during the latter part of this century, the 200,000 or so Peranakans letting traditions fade away. Johnny Yeo, a proudly born-and-bred Peranakan, thought it was about time to call a halt to the cultural slide into oblivion. In his own small way, he has helped start something of a minor Peranakan revival; dining at restaurants such as Nonya and Baba has become popular with young gourmets. ''There were no restaurants in the old days,'' says Yeo. ''It was always cooked at home. It is very hard to cook a good Peranakan meal for the masses. My mother taught my wife, Dolly, how to cook the dishes. It is difficult to train people. We have tried but if Dolly is not around the food tastes different.'' Typical dishes on the moderately priced menu are otak-otak, a fish with coconut milk, chilli and yellow ginger; nonya chap chye, with mushrooms glass noodles and soy sauce; nonya mee, noodles with shrimps, pineapple, cucumber sauce and pounded chilli; and baba ponteh, featuring lean pork, bamboo shoots, mushrooms and green chillis. Yeo's favourite is the buah keluak, a complex dish which takes days to prepare and only minutes to eat. The nut is imported from Jakarta, cleaned thoroughly, chipped to extract the paste, mixed with minced meat, restuffed into the shell and then cooked with fresh chicken, lemon grass, chilli paste and a touch of assam juice. Singaporeans, as fanatical about their food as Hongkongers, have voted Nonya and Baba a hit, filling the 100 seats nightly. Yeo is happy to give a guided tour of the premises, explaining the history behind the display of sarongs, carvings and knick-knacks. ''My great-grandfather married a Malay and eventually had six wives and 26 children. My grandfather had four wives. In those days the wife had to be a virgin and she had to be able to cook. ''Young people try to master the food,'' he says. ''It has become a bit of a yuppie fad.''