Grind the Kashmiri chilis, cinnamon stick, cumin, clove, peppercorns, and turmeric in the mixer to a smooth powder.
Mix with 1 tablespoon of white vinegar to create a smooth paste. Season to taste with salt.
Mix the pork cubes with the spice-vinegar paste in a bowl until evenly coated. Cover the bowl with plastic wrap, and marinate in the refrigerator 3-4 hours or overnight.
Heat the vegetable oil in a Dutch oven or large pot over medium-high heat. Cook and stir the onions, garlic, and ginger until golden brown, about 10 minutes.
Add the pork and its marinade, and cook, stirring frequently, until the pork cubes have firmed, about 5 minutes. Pour in the water, bring to simmer, then reduce heat, cover, and cook until the pork is tender, about 40 minutes. Alternatively, you can also empty the contents into a pressure cooker and cook this for 2 whistles and 10 minutes on slow.
Stir in the green capsicum strips and 1/4 cup of vinegar. Cook uncovered until the green chile peppers have softened and the vindaloo has thickened, about 30 more minutes. Season to taste with salt.
After cooled, shred pork using two forks, mix well with gravy. Should be fairly dry.
Cut puff pastry into desired size squares. I make 3x3 inch squares. Place vindaloo mixture in the middle of each square.
Dampen edges with water. Fold pastry into rectangles, triangles or little pockets. Seal edges down with fork and poke the tops a couple of times to allow venting.
Brush with beaten egg and water mixture and bake at 375 degrees for 20 minutes or till golden brown. Garnish as desired. Serve hot and enjoy!!