To prepare Kaddu ki sabzi, in a heavy bottomed wide wok / kadai, heat the oil. Add the asafoetida, mustard seeds, fenugreek seeds, cumin seeds. Once the mustard splutters, add the pumpkin cubes and toss well to coat with oil and whole spices.
On medium flame, cook the pumpkin for 5 minutes or so, then add all remaining powdered spices, including crushed jaggery, add 1/2 cup of water, cover and cook on low flame. This will take at least 15-20 minutes to cook. Keep checking every 5 minutes, if any additional water is required, adding 1/4 cup at a time, if necessary.
When cooked, you should be able to crush the pumpkin with the thumb with light pressure but the shape should be retained, and the whole dish should not turn into mashed pumpkin.
Adjust the red chilli powder, jaggery and amchoor to suit your taste such that it is a good balance of spicy, sweet and sour. If the pumpkin is inherently quite sweet, you don't have to add much jaggery.
Garnish with finely chopped coriander. Serve with hot pooris.