Spicy, sweet soy sauce for use in many Indonesian dishes, or as a condiment.
Place all ingredients in a large saucepan. The pan should be large enough to accommodate the foam that will be produced when cooking.
Bring to the boil. Reduce heat and let simmer an hour over low heat.
Remove from heat and let sit one hour. Strain and pour into a very clean bottle.
Ketjap keeps well for a year or two at room temperature.