Start by preparing the filling. In a pot filled with water, cook the sweet potato cubes until they are soft, around 8 minutes. Drain the water and let the potato cubes cool down.
Mash the potatoes coarsely, using a fork or a potato masher, and add the peas to it. Give it a good mix.
In a pan, add the oil, and heat it on low heat. Add the turmeric powder, chaat masala, garlic powder, red chili flakes, cumin powder, ginger and saute this for a minute.
Turn off the heat and add the potato-pea mixture.
Add salt to season.
Give the mixture a good stir, so that all the ingredients are well distributed.
Pre-heat your oven to 180 C or 350 F.
Roll out your puff pastry sheet and cut out equal-sized squares.
Place a heaped tablespoon of the filling into each square and fold the side over, forming a triangle.
Press down the sides, sealing in the filling.
Using a pastry brush, brush a little egg wash on the puff pastry.
Transfer the sealed samosas parcels onto a parchment-lined baking sheet and bake it at 180 C (350 F) for 10-15 minutes, until the puff pastry is golden and baked through.
Serve your samosas with chutney or relish of your choice.