Begin by boiling the diced potatoes in salted water until fork-tender, about 10-15 minutes. Drain and set aside.
In a large skillet, heat the vegetable oil over medium heat. Add the cumin seeds and let them sizzle for a few seconds. Then, add the chopped onions, garlic, and ginger. Sauté until the onions are translucent, about 5 minutes.
Add the boiled potatoes and peas to the skillet. Stir in the coriander powder, garam masala, turmeric powder, red chili powder, and salt. Mix well and cook for another 5 minutes, allowing the flavors to blend. Remove from heat and let the filling cool slightly.
Preheat your oven to 400°F (200°C). Roll out one pie crust and fit it into a 9-inch pie dish.
Spoon the samosa filling into the prepared pie crust, spreading it evenly.
Roll out the second pie crust and place it over the filling. Seal the edges by crimping with a fork. Cut a few slits in the top crust to allow steam to escape.
Bake in the preheated oven for 30-35 minutes, or until the top crust is golden brown.
Allow the pie to cool for a few minutes, then garnish with fresh cilantro if desired.