Toast the whole spices in a dry skillet over medium heat until fragrant, about 2–3 minutes: Cumin Seeds, Coriander Seeds, Black Peppercorns, Brown Mustard Seeds, Cloves, and a stick of Cinnamon. Let cool.
Soak the Dried Kashmiri Red Chilies in hot water for 10–15 minutes to soften, then drain (reserve a little soak Water).
In a blender, combine the softened chilies, the cooled toasted spices, Garlic, Ginger, a pinch of Ground Turmeric, a generous pinch of Salt, and White Vinegar. Add a splash of the reserved soak Water or extra vinegar as needed and blend to a smooth, thick paste — this is your vindaloo masala.
Cut the Pork Shoulder into 1½–2 inch cubes. In a bowl, coat the pork with the vindaloo masala, stir in a small piece of grated or chopped Jaggery (to balance heat and acidity), cover, and refrigerate to marinate for at least 1 hour or preferably overnight.
Heat a few tablespoons of Neutral Oil in a heavy-bottomed pot over medium-high heat. Working in batches, brown the marinated pork on all sides, then remove and set aside.
In the same pot, add the sliced Onion and cook over medium heat until deep golden and caramelized, scraping up any browned bits from the bottom of the pan.
Return the browned pork to the pot with the onions, add any remaining masala from the bowl, a splash of White Vinegar to brighten, and about 1–2 cups of Water (enough to just cover the meat). Bring to a gentle simmer, cover, and cook over low heat until the pork is very tender, about 1–1½ hours (or pressure-cook for 20–30 minutes).
Uncover and simmer briskly to reduce the sauce to your desired thickness. Taste and adjust seasoning with more Salt, a little extra Jaggery if needed to balance acidity, or a splash of White Vinegar for brightness.
Serve the vindaloo hot with steamed rice or bread, letting the deep, tangy, and spicy sauce shine.
