Cut bittergourd into half lengthwise and with a sharp edged spoon scrap out the red seeds and cottony pith until no trace of white is left inside the gourd halves. Slice gourd into cubes. Soak the slices in salted water for 56 minutes. Rinse the gourd and drain well.
Heat enough oil in a wok and deep-fry tempe slices until lightly golden. Drain from oil. Leave 45 tablespoons oil in the wok and sauté ground spice ingredients, lemon grass and galangal until fragrant.
Mix tamarind pulp with the thin coconut milk and strain the mixture into the wok. Bring to a boil.
Add in the bittergourd, fried tempe and prawns. Stir until cooked before adding chillies and tomato. Pour in the thick coconut milk and finally add seasoning to taste. Dish out and serve with hot rice.