Dry roast each of the above whole spices separately, cool and grind to a powder in a mortar and pestle or spice grinder.
Wash the pork, pat dry. Sprinkle with turmeric powder, and red chilli powder if using, Mix well, and set aside.
Chop the onions finely. Scrape the ginger, peel the garlic, and grind together to a smooth paste in a food processor. Slit the green chilies and set aside.
Heat the sesame oil in a pressure cooker, and when hot, add the chopped onions. Stir and fry over medium heat until translucent. Add the ginger-garlic paste, and fry until the raw smell disappears.
Add the marinated pork cubes, raise the heat and fry until the meat changes colour.
Now reduce the heat, add the dry-roasted spices, and mix until the cubes of pork are well coated with the spice mixture. Add salt to taste, 2 cups hot water (more or less, according to the thickness of gravy you prefer) and bring to a boil over medium heat. Cover, reduce the heat to low-medium, and pressure cook for about 20 minutes.
Remove from the heat. Allow the pressure to drop. Test for doneness. The pork should be tender but firm.
Return to the heat, toss in the slit green chillies, add the Kachampuli, and simmer for about 5-7 minutes over low heat before turning off the heat.