Soak the dry red chillies in vinegar for almost one hour.
Dry roast coriander seeds, cumin seeds, mustard seeds, fenugreek seeds, black peppercorns, cinnamon stick, cardamom, clove and after cooling them take into a blender and blend them to dry powder.
Now add ginger, garlic and soaked chilli along with the vinegar into the blender and make a smooth paste and add tamarind to this paste.
Marinate the chicken pieces with the prepared paste for approximately 1 hour.
Heat oil in a pan and fry the chopped onions until they are golden brown in color.
Next add the marinated chicken and add little turmeric powder and cook under medium flame by covering with a lid. Stir in between.
After cooking for 10 to 15 minutes, add the tomato puree and cook until the raw smellof tomato is gone.
Add sugar and salt as per the taste.
Next add one and half cup of water and allow the chicken to cook for some more time.Once the gravy turns thick switch off the gas and Chicken Vindaloo is ready to serve