Take a mixer bowl, add peppercorns, coriander seeds, cumin seeds, fenugreek seeds, mustard seeds, cloves, cinnamon sticks, green cardamom, garlic pods, chopped ginger, white vinegar and Kashmiri red chillies, add a little water to the same and grind it into a fine paste.
Take about 500gms of boneless chicken on a bowl, add the freshly grated paste of the spices into the chicken pieces and mix it well.
Now cover the bowl with a lid and let the chicken marinate for 1 to 1 ½ hours.
Take a wok or kadhai, add about ½ cup vegetable oil, add the chopped onion and fry it until soft or light golden brown in color. Add the green chillies and sauté it for 2 more minutes before adding the chopped tomatoes. Mix all the ingredients well and let it cook for 4 to 5 minutes. Now add a little salt and about 1tsp of jiggery to the kadhai and give it a quick stir, let all the ingredients cook until the tomatoes are soft and the raw smell of onion and tomato is gone.
Now add the marinated chicken along with the paste and mix all the ingredients well. Cover the lid and let it cook for 10 to 12 minutes in medium flame. Remove the lid, if the chicken has started leaving oil and the raw spell of spices is no longer there, add 1 cup of luke warm water to the same. Add salt to taste, give it a good stir, cover the lid and let it cook for 10 more minutes.
Remove the lid, if the chicken is tender by now, and the gravy has thickened, turn off the heat and garnish it with some fresh chopped coriander.
Your Chicken Vindaloo is ready to be served. Enjoy!