Prepare the Vindaloo Paste: Lightly toast the cumin and mustard seeds in a dry pan over medium heat until they pop. Transfer the toasted seeds to a blender. Add the dried chillies, garlic, ginger, turmeric, cinnamon, cloves, black pepper, and salt. Blend with vinegar until it forms a smooth paste.
Marinate the Pork: Thoroughly coat the pork cubes with the Vindaloo paste in a large bowl. Cover and refrigerate to marinate for at least 2 hours, preferably overnight, to enhance flavour absorption.
Cook the Curry: Heat the vegetable oil in a large pot over medium heat. Sauté the onions until golden brown. Add the marinated pork and stir frequently until the meat is well browned on all sides. Mix the pureed tomatoes and tomato paste, and cook for 2 minutes. Pour in the water and bring to a boil. Then reduce the heat to low, cover, and simmer for about 1 hour, or until the pork is tender and the flavours are well blended.
Final Adjustments: If the curry sauce is too thick, adjust the consistency with more water as needed. Taste and adjust the seasoning, possibly adding more salt or vinegar to balance the flavours.
Garnish and Serve: Just before serving, sprinkle with chopped cilantro for a fresh herbal contrast. Serve the curry hot, accompanied by steamed rice or warm Indian bread like naan or roti.
