Black pork curry is the most famous Sri Lankan pork dish that everyone loves. The fatty pork pieces cooked in aromatic spices in low heat for a long time until they melt in your mouth. Try this curry once, you're gonna think of this curry every time you see a piece of pork.

marinate the pork pieced with all the marinating ingredients given in the list above. Let it marinate for at least 30 minutes to overnight in the fridge. ( longer marination is better)
Crush ginger and garlic in mortar and pestle to a rough paste.
Crush the lemongrass piece with the blunt side of your knife to release the oils.
Heat a pot and add coconut oil. When the oil starts to heat up add 1/4 tsp salt, chili powder, and unroasted curry powder. Fry them in low heat until the spices become dark brown to almost black. Turn off the heat if it's smoking too much. Stir continuously.

To that add crushed ginger and garlic, powdered/crushed cardamom and cloves, pandan leaves, curry leaves, and lemongrass. Mix well with the spices.
Then add chopped onion and mix well with everything else. Saute for about a minute.
Add the marinated pork pieces to the pot. Mix well with the onions and spice mix. Saute for about a minute.
Then add 1/4 cup of water. Mix. Cover and cook on very low heat.
In about 30mins, taste the gravy and see if it has enough salt. If not add a little bit more. Cover again and cook in very low heat for about another 30 mins until the gravy thickens up and the pork becomes tender.
The longer you cook, the darker it gets. If you feel like the curry is drying out, add a bit more water and continue cooking.
You can cook it until there's no gravy left and serve it as dry curry too. I'm attaching a photo from a different time I cook pork using this same recipe. Just to show you that you can cook it this way too.