Marinate prawns with 2 tsp red chilli powder, turmeric powder and salt.
Shallow fry in coconut oil. Keep aside.
In the same pan, add more oil if need and saute the onions until browned.
Meanwhile roast the coconut. Add coconut in a pan and roast it on medium flame until it turns golden brown in color stirring constantly.
Grind it into a paste with a little bit of water.
Add green chillies and ginger garlic paste to the onions. Stir around for a minute on low flame.
Add 1 tsp of red chilli powder, coriander powder, turmeric powder and garam masala powder. Cook for a minute.
Add the coconut paste to it and mix to combine.
Add salt.
Drop in the fried prawns and mix. Cover and cook for 10 minutes on very low flame.
Your filling is ready.