Marinate the cleaned pork pieces with salt, turmeric powder and 1.5 tsp chopped ginger for 10 mins. Add 1/2 cup water to this and pressure cook for 1 whistle on high flame (refer notes). Keep it closed till pressure drops.
Heat oil in a wide pan and add all the ingredients listed under "to roast and grind". Fry it on low flame, till the coconut turns golden brown. Remove from fire and let it cool. Grind the roasted ingredients. Make sure you pulse it at regular intervals than grinding in one go, the ground mixture should be in powder form and not oily.
Heat oil in a deep and wide pan. Add sliced onion and cook. When onion becomes soft, add 1 tsp chopped ginger and curry leaves. When onion becomes golden brown, add turmeric powder, chilli powder and coriander powder. Mix well and fry for 2-3 mins. Add chopped tomatoes and salt. When tomatoes become soft, add cooked pork along with the water. Mix well.
Bring it to aboil and let it simmer till the gravy is almost dried. Add powdered coconut mixture to the pork and mix well. Cook for 5-7 mins on low flame or longer of required.
Notes
I used the thigh portion of Pork with bone. The cooking time of pork may vary, so adjust the pressure cooking time accordingly.It takes some time for the flavour to settle in and it tastes better the next day. Also the colour tends to deepen as it rests. If you want the pork pieces to be covered with coconut masala, add 1-2 tbsp hot water and heat on stove top.It keeps well in the fridge for 3 days. it's better to reheat it on stove than microwave.If you want it to be extra spicy, add 2 chopped green chilly along with sliced onion while making the masala.