Mix 2 tbsp of garlic (roughly chopped), salt to taste, 1 tsp of turmeric powder, 2 tsp of red chili powder and 2 tbsp of water in a bowl. Squeeze in 2 tbsp of lemon juice and mix again.
Apply the masala mixture on 1.5 kg of fish (King Fish/Surmai) and let it marinate for 30 minutes.
Roughly chop one medium-sized onion, 10 pieces of green chilies, 10 pieces of garlic, and a piece of ginger about 2 inch in size. Blend them all with ½ cup of coconut milk. Keep aside.
Grate a cup of fresh coconut and blend nicely with 1 tbsp of water.
Fry the marinated fish in a pan with 2 tbsp of cooking oil over a medium flame. Remove after flipping and frying for 2 to 3 minutes on each side.
Fry 1 tsp of mustard seeds, 1 tsp of cumin seeds, 15 pieces of curry leaves, ½ tsp of carom seeds and ½ tsp of fenugreek seeds in the remaining oil for a minute until they change color.
Add the blended fresh coconut. Mix, cover and cook well until the oil separates.
Add the coconut, onion, ginger garlic and green chili paste. Mix, cover and cook for another 10 minutes.
Add salt to taste, ½ tsp of turmeric powder, 2 tsp of red chili powder, and 2 tsp each of roasted, crushed cumin seeds and coriander seeds. Mix and cook for another 5 minutes. Then add ¼ cup of yogurt and 1 tbsp of water followed by 1 tbsp of tamarind paste. Mix, cover and cook for 2 minutes on a low flame.
Add a cup of water. Add the fried fish pieces followed by 1 tsp of garam masala powder, 1 tbsp of dry, crushed fenugreek leaves (Kasuri methi), 6 pieces of green chilies (slit into half), 10 pieces of curry leaves and a handful of finely chopped coriander leaves.
Cover and cook on a low flame to achieve the final consistency. Transfer it to a serving plate.
Garnish it with a few finely chopped coriander leaves. Your tasty and spicy homemade fish coconut milk curry is ready.