Prepare the prawns by cleaning them and then marinating them with a pinch of salt, turmeric, and lime juice. Let it rest for 15-20 minutes.
Now make the masala paste by blending grated coconut, green chillies, ginger, garlic, and spices and forming a smooth paste.
Then, heat oil in a pan and saute finely chopped onions, curry leaves,and mustard seeds and cook until the onions turn golden-brown.
Stir chopped onions and other spices in it and cook until the tomatoes soften and the oil starts to separate.
Add the coconut masala paste to the pan and then cook for another few minutes.
Now, finally add the marinated prawns to the pan and pour coconut milk into it. Simmer the curry on low flame and cook for 5-7 minutes or until the prawns are cooked.
Squeeze lemon juice into it and garnish it with freshly chopped onions. And serve delicious Kerala prawn curry with naan or rice.