To begin, hard boil the eggs. Peel and make gashes along the length so that the masala can soak in.
Prepare the vindaloo paste by grinding together Kashmiri red chillies, ginger garlic paste, cinnamon, cloves, peppercorns, cumin seeds, coriander seeds, and fenugreek seeds with white vinegar into a smooth paste. Add a bit of water if required. You can de-seed the chillies if you want it less spicy. Keep aside.
Heat 1 tbsp of oil in a pan. Saute the eggs until they lightly colorize. This adds extra flavor to the egg curry.
In the same pan, heat 2 tbsp of oil. Add in the chopped onions and saute until translucent.
Add the vindaloo paste, salt, and turmeric powder. Mix well and cook until the oil begins to appear on the sides.
Now add in the boiled eggs and mix until they are well coated. Add water to make the gravy and bring it to a boil.
Add in the tamarind paste and brown sugar. Mix well, reduce the heat, and continue to cook for a few minutes.
Adjust the gravy as per your taste. Check the salt and add more if required. The Hot & Spicy Egg Vindaloo is ready to serve.