Nuoc Mam - Vietnam's Culinary Pièce de Résistance
To a Vietnamese, 'nuoc mam' is what olive oil is to an Italian. The salty brown fish sauce is made from fermented anchovies, and is stronger than 'nam pla', the Thai equivalent. Straight from the bottle, it’s an acquired taste, but mixed with rice vinegar, lime juice, garlic, and sugar it becomes nuoc mam cham, the familiar spring roll dip.
Used like salt in western cooking and soy sauce in Chinese cooking, good-quality fish sauce imparts a distinct aroma and flavour of its own. No respectable Vietnamese kitchen would be without it – it's a key element of the country’s cuisine both as an ingredient and as a sauce. Genuine fish sauce is the juice from the flesh of fish extracted by a process of prolonged salting and fermentation. It's made from small fish, usually saltwater, that would otherwise have little value for consumption. Anchovies and related species are commonly used as they are plentiful in the coastal waters of the Gulf of Thailand and the East Sea. Larger fish also make good fish sauce, but are relatively more expensive due to their value as a food fish and thus seldom used for the purpose. For fish sauce to have a pleasant, fragrant aroma and taste, the fish must be very fresh. As soon as fishing boats return with their catch, the fish are rinsed and drained, then mixed with sea salt -- two to three parts fish to one part salt by weight. They are then pressed into large earthenware jars, lined on the bottom with a layer of salt, and topped with a layer of salt. A woven bamboo mat is placed over the fish and weighed down with heavy rocks to prevent the fish floating when the water inside them is extracted by the salt and fermentation process. The jars are covered and left in the sun for nine months to a year. From time to time, they are uncovered to expose the mixture to direct, hot sunshine, which helps to ‘digest’ the fish and turn them into fluid. Periodic ‘sunning’ produces a superior fragrant fish sauce with a clear, reddish brown colour. Eventually, the liquid is removed from the jars, preferably through a spigot on the bottom so that it passes through the layers of fish remains. Any sediment is removed and the filtered fish sauce is transferred to clean jars and allowed to air in the sun for a couple of weeks to dissipate the strong fishy odour. It is then ready for bottling. The finished product is 100-percent, top-grade, genuine fish sauce.
Second and third grade fish sauces are made by adding salt water to cover the fish remains, leaving them for 2-3 months each time, then filtering before bottling. Finally, the fish remains are boiled with salt water, then strained out and discarded, to produce the lowest grade fish sauce; or they may be added to other fish remains from the first fermentation in the process of making second-grade sauce. Because the flavour is substantially reduced with each fermentation, top-grade fish sauce is frequently added to the lower grades to improve their flavour. In practice, few manufacturers market top-grade fish sauce, mixing it with second and third grade sauces instead in order to produce larger quantities that can still qualify as genuine fish sauce.
Fish sauce is high in protein (as much as 10% in the highest grade), and contains all the essential amino acids that the body requires for growth and regeneration. It also provides a rich supply of vitamins, riboflavin and niacin, and nutrients such as calcium, phosphorous, iodine and iron.
Fish sauce is manufactured in several places in Vietnam, and there is much rivalry between the different products. The Mekong and Phan Thiet varieties are strong contenders, but there seems a general agreement among unbiased epicures that Phu Quoc wears the fish sauce crown!