Chop the chicken into medium-sized pieces. Rub with turmeric and salt and wash with water.
Grind the first 6 ingredients given under "for marination" with a little water. Marinate the chicken in this paste with the curd, turmeric powder, and salt for 30 minutes.
In about a tsp of oil, fry all the items starting with coriander seeds and ending with poppy seeds as given in the "for masala" list. Add the fenugreek seeds, ajwain, and poppy seeds last of all. Let it cool.
Next roast 1 cup of grated coconut till it's nice and brown. Cool down and grind this together with the roasted spices and water to make a paste.
Soak the tamarind in ½ cup water for some time, squeeze it and keep ready. Extract ¼ cup of coconut milk by grinding the ¼ cup of coconut with some water. Julienne the onion to thin strips.
In a frying pan take 2tbsp of oil and saute the onion. Once it turns pink and fries a bit, add the marinated chicken. Saute till the meat changes color.
Next, add the ground masala paste, saute for a minute and then add the tamarind water, turmeric powder, chilly powder and salt as needed. Add another ½ cup water and let cook till the chicken is done and the gravy thickens.
Finally, add the coconut milk and switch off the stove when it comes to a boil. Squeeze the lemon and garnish with ghee and coriander leaves. I served it with plain white rice. Goans prefer to have this mostly with pavs or dinner rolls, and sometimes with flatbreads and rice.