1. In a heavy 8- to 10-inch skillet, heat the oil over moderate heat until a light haze forms above it. Drop in the onions, garlic and salam leaves and, stirring frequently, cook for about 5 minutes until the onions are soft and transparent but not brown.
2. Watch carefully for any sign of burning and regulate the heat accordingly. Add the trassi and mash it thoroughly with the back of a spoon. Stir in the chili, lime peel, ginger and salt, and when they are well mixed add the coconut milk and tamarind water.
3. Stirring occasionally, bring to a boil over high heat. Reduce the heat to low and simmer uncovered for 5 minutes until the chili strips are tender but still in-tact. Add the sugar and stir until it dissolves completely.
4. Sambelan sauce is the base for a variety of Indonesian side dishes, many of which are made with foods already cooked, such as sambelan telor or sambelan hati ajam.
