In a large wok or kadhai, heat oil and add cumin seeds. Once they start to splutter, add coriander powder, red chilli powder, turmeric, amchoor and salt. Cook for 10 seconds and add the sliced potatoes with two tablespoons water.
Mix well and cover and let this cook for 5 minutes. After 5 minutes, add the sliced onions, mix well and cover and cook on slow for approx 15 minutes or till the potatoes are cooked through. Stir once or twice in between to keep it from sticking to the bottom. Check if the potatoes are done, or cook for a few more minutes. Taste and adjust seasoning and serve hot.
Veg Prep: You can either slice the potatoes and onions thinly or cut them into small pieces (approx ½ inch). The larger the cut, the longer it'll take to cook. A small dice will cook even faster.
Spices: If you don't have some of these spices, feel free to substitute with a generic curry powder. Do not use garam masala as a substitute, which has a much stronger flavour
The cooking time can vary slightly based on the size of potatoes and the quantity.