Add oil to a large skillet or wide pot on medium high heat. Once oil is hot, add cumin seeds and green chilis. Let sizzle for few seconds.
Add the frozen veggies (thawed) and stir for a few minutes. Add garlic, remaining spices, salt and mix well. Cook this mixture for a few minutes and then add the potatoes and incorporate well. Continue to cook for 3-4 minutes. If potato pieces are too large- use a potato masher.
Remove the mixture from heat and let it cool completely.
Remove the puff pastry from the package and cut each sheet into three long columns, and each column into thirds so you have three square shapes.
Place a spoonful of the potato filling in the center of each square. Using your finger, spread water along all four outer edges of the pastry. Carefully close the pastry by bring the top flap to the bottom and using the edges of a fork to seal the perimeter of the puff pastry. Then with a knife, pierce each puff pastry two or three times gently (so air can escape while they are baking). Repeat this step in assembling the pastries until you have used all of the filling.
Place all the puff pastry on a lightly greased baking sheet. Using a brush, spread egg wash (one whisked egg) lightly over each puff pastry. Place in the middle rack and bake for 15-18 minutes until golden.
Serve with chai, cilantro chutney or however you wish!
Recipe by The Chutney Life at https://thechutneylife.com/recipes/appetizers/veg-masala-puffs/