To make the filling, place each boiled potato on a chopping board and use a heavy fork to mash the potato (the way you would if you were making smashed potatoes), then cut into small bits. You want your potato filling to be a crumbly, semi-mashed mix for an authentic filling, not cut in a neat dice.
Preheat the oven to 425 degrees F.
Heat the oil in a skillet. Add the cumin seeds and as they darken and become fragrant, add the onions, ginger, garlic and green cilantro, chili peppers or red pepper flakes. Stir to mix and saute until the onions turn translucent and start to change color.
Add the turmeric, stir it in, then add the crumbly potatoes and salt and lemon juice. Mix well and saute for a couple of minutes, then turn off the heat. Your potato mixture should be very dry.
To make the pastry squares, place one puff pastry sheet on the countertop. Use the folds in the puff pastry as a guide to cut into three strips. Cut each strip further into three equal squares. You should have eighteen squares in all -- nine from each sheet.
Use water to moisten one of the pastry squares along the edges. Place a couple of tablespoons of filling in the middle. The more crumbly your filling is, the more you'll be able to accommodate on the square. Take another pastry square and place it over the filling and press the edges of the top and bottom squares together with your fingers to seal them, making a pocket. Use the tines of a fork to press down on the edges -- this also creates a decorative pattern. Use a sharp knife to cut a cross on the top of the square.
Continue doing this for the remaining pastry and filling. Then place the squares on a baking sheet, at least an inch apart. Bake in the preheated oven 15 minutes until gold and crispy. You can brush on some vegetable oil on the tops of the squares before baking for a deeper gold color to your puff pastry squares.
Serve hot or warm or at room temperature. To reheat, heat the oven to 350 degrees and pop in for 2-3 minutes or until hot. These will keep in the refrigerator for about a week.