Special equipment: spice grinder
Using a spice grinder, grind the cumin seeds, coriander seeds, peppercorns, cardamom seeds, cloves, and cinnamon to a fine powder.
In a food processor, blend the ginger, garlic, chiles, and white wine vinegar, to a paste.
Mix the ground spice mixture with the paste until well combined, and season with a pinch of salt, to taste. Rub the mixture all over the pork using your fingers, and then set the pork aside, covered, and placed in the refrigerator to marinate for 1 1/2 to 2 hours.
Heat 4 tablespoons of oil in a nonstick pan. When the oil is hot, add the onion, and fry for 3 to 4 minutes, or until golden brown.
Add the marinated pork pieces, and fry for 6 to 7 minutes, turning once, or until golden-brown on all sides. Reduce the heat to low, cover the pan with a lid, and cook for 35 to 40 minutes, stirring occasionally, or until the pork is tender. Add small splashes of boiling water to the pan as necessary, if the juices in the pan dry out. Add as little water as possible as the resulting sauce should be quite thick.
Heat the remaining oil in a separate pan over medium heat. When the oil is hot, add the mustard seeds. Caution: The mustard seeds will start to pop. Keep the pan well away from your face and eyes. Be careful of the popping mustard seeds and the splatter of oil. Once the mustard seeds start to pop, add the cashew nuts, and fry for 2 to 3 minutes, stirring occasionally, or until the nuts are golden-brown.
To serve the dish, either divide the rice, if using, among 4 serving plates, spoon the vindaloo alongside and pour the fried cashew nuts and mustard seeds over the vindaloo, or alternatively spoon the vindaloo into the center of 4 wheat tortillas, if using, sprinkle with chopped lettuce, and sour cream and roll up into parcels.
*Can be found at specialty Asian markets. Add as little water as possible when cooking a vindaloo, and only add more water when all the liquid from the ingredients used has cooked off. Remember that a vindaloo that sits overnight tastes even better the following day.