Begin by boiling or steaming the diced or wedge-cut potatoes until they are fork-tender. Once cooked, drain the potatoes and allow them to cool in a colander or wire mesh strainer.
Peel the parwal (pointed gourd) using a vegetable peeler. Cut the peeled parwal in half. If the parwal is mature, remove the seeds to ensure a smooth texture in the curry.
In a pot, heat the cooking oil over medium heat. Add the cumin seeds, curry leaves, and thinly sliced green chili (hari mirch), allowing them to sizzle and release their flavors.
After a couple of minutes, add the steamed potatoes and the cut parwal. Sprinkle in the turmeric powder, Kashmiri red chili powder, coriander powder, asafoetida (hing), amchur (mango powder), and salt. Toss until the potatoes and parwal are golden with spices.
Pour in 1 cup of water, and stir the ingredients to combine them well. Allow the curry to cook on medium heat for about eight minutes or until the parwal becomes tender and approximately half of the liquid has evaporated and thickened due to the starches in the potato.
Once the Parwal Ki Sabji reaches the desired tenderness and consistency, it's ready to be served. Garnish the curry with fresh cilantro leaves and optionally add thinly sliced green or red chilies. Optionally dust the dish with parwal masala or chaat masala powder.