In a food processor or blender, grind down onion, ginger, garlic, mustard seeds, cumin seeds, cinnamon sticks, peppercorns, and cloves, using just enough vinegar (to keep mixture moving in blender or food processor until thick paste is made). Set aside.
Add remaining vinegar and 2T water to a bowl. Add pork and rinse with water mixture. Pat meat dry with paper towel.
In another bowl, mix pork with wet rub and marinate for 8 hrs or overnight.
When ready to cook, set pressure cooker to "sear", adjust time to 15 minutes, add oil, and press "start/stop". When hot, add pork, curry leaves and cook until brown, 2 to 3 minutes. Add pork stock, tomatoes with juice and turmeric.
Close and lock lid, set pressure cooker to "meat/stew", adjust time to 30 minutes, and press "start/stop".
When done, quick release and make sure all pressure is released before opening lid. Carefully open lid and stir. Sauce should be thick. Season to taste. Serve with cooked rice and garnish with cilantro.