Add dry Kashmiri red chilies, coriander seeds, cloves, cinnamon stick, green cardamoms, black peppercorns, cumin seeds, and mustard seeds to a skillet. Dry roast on medium heat until fragrant
Add the roasted spices to a high-speed blender along with ginger, garlic, white vinegar, tamarind paste, and water.
Make a smooth paste.
Add oil in a pan. When the oil is hot, add 2 cups of chopped onions and fry till golden brown.
Add 2 lb (1 kg) bone-in skinless washed chicken pieces (cut into 1 and ½ inch chunks) to the pot and fry on high heat for 3-4 minutes.
Add 1 cup canned tomato puree and the vindaloo masala paste that we made earlier to the pot and mix well.
Now add 2 teaspoon salt, 1 teaspoon turmeric powder, and 1 cup water to the pot and stir gently.
Cover the pot with a lid and cook on low heat for 45-50 minutes until the chicken is cooked well.
Add ½ teaspoon sugar and cook for another minute. Chicken vindaloo is ready to be served.