1. In a heavy 8-inch skillet or saute pan, heat the oil over moderate heat until a light haze forms above it. Drop in the shallots, or scallions, and garlic and, stirring frequently, cook for 3 or 4 minutes, or until they 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.
3. Pour in the chicken stock and bring to a boil over high heat. Stirring constantly, add the peanuts, Ketjap Manis, lime juice, ginger and chilies.
4. Reduce the heat to low and, stirring occasionally, simmer uncovered for 10 minutes, or until the sauce is thick enough to coat the spoon heavily. Serve at once.
5. If necessary, the sauce may be prepared ahead and reheated. In this event it may thicken as it stands. Thin it if necessary with a tablespoon or more of water.
6. Katjang is traditionally served with Sate Ajam.
