Dry roast red chillies, fenugreek seeds, peppercorn, cumin seeds and coriander seeds for 2 minutes till fragrant.
In a blender the dry and roasted spices all with chopped coconut till you get a thick paste. Use some water if needed.
Now heat oil in a pan and fry finely chopped onions till golden brown.
Now add the coconut spice paste to this along with ginger garlic paste and cook till the raw smell is gone and the curry looks glossy. It took me about 15 minutes. Make sure that the masala paste does not burn.
Now add 1.5 cups prawn stock for more prawn flavour or any other stock or water to the masala. Bring to a boil.
Now add the prawns along with tamarind paste and cook for just about 2-3 minutes. Turn off the heat and let the prawns soak in the flavour.
Garnish with coriander leaves and serve hot with boiled rice or appams. Your prawn gassi is ready.
Using prawn stock enhances the flavour of the curry but you can use plain water as well or veg or chicken stock if you so wish.
I generally keep the shells and heads of the prawns when I devein them and make a quick broth by boiling them in water and straining.
You can use the same recipe to make fish curry Mangalore style by using any firm fish. Just increase the cooking time suited to the fish you are using.