Make Spiced Potato-Pea Filling: Heat 2 tbsp oil in a skillet over medium heat. Add cumin seeds and fennel seeds; let them sizzle for 20 seconds. Add grated ginger and green chili, cooking for 30 seconds.

Add coriander, ground cumin, garam masala, turmeric, amchur (or lemon juice), and salt. Stir for 15 seconds.

Add the coarsely mashed potatoes and green peas. Cook for 2 to 3 minutes, stirring to coat the potatoes in spices. (Keep some potato texture; do not mash into smooth baby food). Remove from heat, stir in cilantro, and let cool to room temperature.

Prep Pastry & Oven: Preheat your oven to 400°F (204°C). Line a large baking sheet with parchment paper.

Unfold the thawed puff pastry sheets on a lightly floured surface. Gently roll each sheet with a rolling pin to smooth out fold lines into an approximate 10x10-inch square.

Cut each pastry sheet into 4 equal squares (yielding 8 squares total).

Fill and Seal: Place about 2 generous tablespoons of cooled potato filling into the center of each square. Brush edges lightly with water or egg wash.

Fold one corner diagonally over the filling to form a triangle (or fold into a rectangle). Press edges firmly to seal, then crimp edges with a fork to lock in the filling.

Bake: Transfer puffs to the prepared baking sheet, leaving 2 inches between them. Brush the tops lightly with the whisked egg wash (this guarantees rich golden browning).

Bake at 400°F (204°C) for 18 to 22 minutes until puffed, crisp, and deeply golden brown. Let rest on the baking sheet for 5 minutes before serving hot with sweet tamarind chutney or mint chutney.