Soak the tamarind in 200ml of water for 20 minutes.
Blend the spice paste ingredients with 5 tablespoons of water into a smooth paste.
Heat oil in a large pan and fry mustard seeds, fenugreek seeds, and shallots until brown.
Add green chillies, ginger, curry leaves, and salt, then cook for 5 minutes.
Stir in the spice paste and cook for 5 minutes before adding prawns and palm sugar.
Add the tamarind liquid and simmer for 12 minutes until prawns are cooked.
Adjust sauce consistency with 100ml of hot water or fish stock if necessary.
Serve the curry in bowls accompanied by steamed rice.