Heat a dry frying pan over medium heat and toast the cumin seeds, coriander seeds, cloves and chili powder for 1 minute. Grind the spices in a mortar or blender with the coconut, garlic, ginger, coconut vinegar (optional) and 50 milliliters of water to a fine spice paste.
Mix the shrimps with the turmeric powder and salt. Cover and let marinate for 20 minutes.
Heat the oil in a frying pan over medium heat and sauté the onion. Cook for a 10 minutes. Turn the heat up a bit, add the spice paste and fry, stirring, for 10-15 minutes until an orange-brown whole.
Add the marinated prawns and tamarind and bring to the boil. Saute the prawns for 5 minutes.
Turn off the heat and finally stir in the sugar. Garnish with the coriander. Delicious with rice.