Palm sugar is a rich, caramel-like sugar made from the sap of sugar palm trees. Ranging from light to dark brown in color, palm sugar comes in jars in a single mass, soft enough to spoon out, or in hard, small blocks that must be crushed into smaller pieces before use. Since palm sugar is not highly processed, its sweetness can range slightly from batch to batch. Use regular brown sugar or, if you can find it, coconut sugar as a substitute.