Palm Sugar and Phetchaburi

Phetchaburi lies on the western shore of the upper Gulf of Thailand, in the same coastal belt of coconut and palm country as Samut Songkhram, and is long associated with the sugar tapped from the sugar palm, Borassus flabellifer, known in Thai as tan. David Thompson in Thai Food treats the sweetener of this country as the foundation of the central Thai kitchen, and Phetchaburi as the place from which its best repute comes.

Palm sugar is the older sweetener of the Thai kitchen, and in the central plain and the western Gulf provinces it was made from the sap of the palm long before refined cane sugar became common. Thompson distinguishes the sugars by their source. The sugar palm, Borassus flabellifer, is tapped at the flower stalk, while the coconut palm, Cocos nucifera, yields a sap of its own, and the sugar of each is boiled down in wide pans until it thickens and sets. The best is pale, fragrant and soft, and it is sold in cakes or pressed into small pots, called nam tan pip, a name that refers to the vessel in which it is set. The character of the sugar is the reason it cannot be replaced by white sugar in the dishes that call for it. Thompson describes it as having a round, faintly smoky and caramel depth, with a sweetness that is gentle rather than sharp, so that it binds the salt of fish sauce, the sour of tamarind or lime and the heat of chilli instead of standing apart from them. It is pounded into curry pastes, melted into dressings, and cooked down with fish sauce and tamarind to make the dark, sticky seasonings of the Thai table. Its use in desserts, where it is cooked with coconut milk, eggs and rice flour, is equally old. Phetchaburi's standing rests on the quality of its palms and the care of its boiling. The sugar palms stand along the flat ground between the rice fields and the sea, and the sap must be gathered while fresh and cooked promptly, since it ferments quickly in the heat. The sugar of the district is prized for its colour and scent, and the same palms supply the fruit and the sap used in local sweets. Thompson is clear that the grade of the sugar governs the result in the pan, and that a cook who has once used the fresh, fragrant cake will find the dull, over-cooked product of poorer makers a poor substitute. For the cook the lesson is one of tasting and adjustment rather than of measurement. Palm sugar varies from cake to cake in sweetness, moisture and depth, so that a recipe gives only a starting point, and the balance of a sauce or curry is settled by tasting against the salt and sour. Thompson counsels softening the sugar by pounding or gentle warming, and keeping it covered so that it does not dry. Understood in this way, the sugar of Phetchaburi is less an ingredient than a measure of the whole coastal landscape that produced it.

At the table, palm sugar supplies the rounded sweetness that holds the Thai balance of salt, sour and heat. Its caramel depth is most plainly tasted in the dressings, the dark seasonings of stir-fries and the desserts cooked with coconut milk.