The shrimp should be cleaned(shell and vein removed, washed well) Apply chili powder , turmeric powder and salt and keep it aside to marinate till you do the dry roasting and grinding.
Heat a wide heavy bottom pan on medium to low heat and put coconut grated whole coriander, whole red chilies, pearl onion sliced, fenugreek seeds and dry roast it.Constantly stirring without letting it become burnt at the bottom of the pan. The coconut should get brown evenly. The whole curry's worth lies in how well u dry roast. Towards the end add coriander powder (optional) and red chili powder, chili powder, turmeric powder and little salt. Keep stirring but switch off the heat. The residual heat on the stove is enough. Let the mix cool down .Then grind to paste adding tamarind water if using paste add it and some water too. Half of the roasted coconut masala to a coarse mixture and the remaining half to a smooth paste. (Check video for guidance)
Now heat the earthenware or pan, pour coconut oil-2 tsp or more, put the pearl onions, green chili and saute till the onions become tender.Pour the ground mix along and let it simmer for 10 to 15 mts. Add enough water to make a thick curry Towards the end add shrimp .Make sure it cooks well. Remove from flame when the gravy becomes thick .
Heat a smaller pan add coconut oil 2 tsp or more add some pearl onions sliced, whole red chili and curry leaves and a green chili slit for flavor when this browns well add a pinch of chili powder so it gets a deep brown color. Season this immediately on the curry. Cover and keep for atlas two hours so the flavors mingle. Then serve.