Blitz the peanuts in a food processor until finely chopped but retaining a bit of texture. Remove to a bowl and clean out the food processor.

Put all of the ingredients for the spice paste in the food processor and blitz until smooth. If needed, add a few tablespoons of water to help it blend together.

Heat the vegetable oil in a non-stick saucepan over a medium heat and fry the spice paste until fragrant. Add the ground peanuts, tamarind, sugar, 1 tsp salt, the ground coriander and kecap manis along with 200ml water. Stir to combine, then taste for seasoning. Cook over a medium-low heat for 15 mins, stirring continuously until the oil has separated from the sauce. Remove from the heat and leave to cool completely, then decant into a sterilised jar or airtight container. Will keep chilled for up to two weeks.