In my last post on Gang Som, someone left an interesting comment on the question of ingredients I use. I've always made a point to say that these exotic ingredients are difficult to give precise measurement for, since they are hardly standardized. This is certainly a problem in writing Thai recipes, because 5 tablespoon of tamarind, for example, will have varying degree of sourness and thickness, depending on the source and the preparation of your tamarind paste.
I think it would be helpful to write about some of the ingredients that I use in my Thai cooking. How to select for quality. What brand(s) I use. How to prepare, use and store. How to properly measure them for the recipes.
The first one I want to begin with is the palm sugar, ubiquitous in Thai cooking and some other Asian cuisines, but not at all in the west.
Palm sugar is made from tapping the sap from sugar palm trees. The sap comes from the flowering stalks, which are at the base of the long leafs. The liquid is then cooked down to a caramel-like consistency, then let harden into blocks or poured into containers for future use.
Thai palm sugar is different from Malaysian or Indonesian palm sugars that are also available at Asian markets. They are lighter in color, in the shade of light brown rather than very dark and nearly black brown, and have a far less smoky flavor. If you want to faithfully follow a Thai recipe, then I suggest you buy palm sugar from Thailand for your Thai cooking. If you have no choice but the darker Indonesian or Malaysian ones, I would use only half the required amount and supplement with regular white sugar to the desired sweetness.
Good quality Thai palm sugar is light brown in color, and hard, but not completely rock hard. The color is important, because too dark it would be the smoky Indonesian sugar, and too light a color is usually an indication that there is white sugar added in the palm sugar, a practice that is sadly not uncommon in Thailand among unscrupulous merchants, since white sugar or cane sugar is far cheaper than palm sugar.
The palm sugar in the photo on top of this post is pretty close to the perfect color. Not too light, and certainly not too dark. If you look closely, you can also see that the sugar is not completely crystalized. It is hard, but still somewhat crumbly and it is actually possible to cut it with a knife to smaller pieces. The best test for is is to cut a small piece and chew on it. The sugar should crumble when you chew. If you broke a teeth or two, then it's probably not a very good palm sugar. I wouldn't buy that brand again.
Palm sugar comes in a few forms, in small rounds like in the photo, in larger rounds, in a plastic jar, or even in a can. I find the small rounds that come in a plastic bag the most user-friendly. I keep mine in an airtight container. To use, I chop each round into smaller pieces to make it easier to melt.
When I need to do a precise measurement for a recipe, I put a few small rounds (about 50g or 1.5oz each) into a bowl and add to that one teaspoon of water per round. The bowl goes into the microwave for about 30 seconds (a bit longer if you are melting a large quantity, the sugar will melt enough so you could stir to mix well with the water, and you will be able to portion it easily with a measuring spoon.
You can also do this with a larger round or palm sugar, you just need to chop it up a bit to smaller chunks. I usually don't use palm sugar in a plastic jar or in a can, finding it nearly impossible to scoop out the hardened sugar from those containers. Also, I'm not so keen on nuking the entire plastic jar. I don't think that cheap plastic would do so well in the microwave.
For most Thai recipes, if you have no access to palm sugar at all white sugar will do in a pinch. I have actually used a mixture of maple syrup and white sugar as a replacement even, to add a bit more complexity than using white sugar alone.
There you have it, palm sugar 101. Leave a comment if you had any other question.