Boil and peel 3 large potatoes.
Coarsely crush the potatoes with your hand. You don't have to mash the potatoes.
Add 1 cup curd (yogurt) in a mixing bowl along with 1/2 cup water.
Beat the curd and water mixture till smooth.
Heat oil in a kadai or pan over medium heat. When oil becomes hot add cumin seeds (jeera) and let them crackle. Then add heeng (asafoetida) and green chillies.
Next add turmeric powder (haldi), red chilli powder, coriander powder (dhania) and dry ginger powder (saunth). Roast the spices for a few seconds. Do not add salt at this stage.
2/3 Teaspoon Red Chilli Powder, 1/2 Teaspoon Haldi (Turmeric Powder), 1/2 Teaspoon Dhania Powder (Coriander Powder), 1/2 Teaspoon Saunth (Ginger Powder)
Add the coarsely mashed potatoes to the pan.
Stir to coat the potatoes in the spices and lightly roast them for a minute.
Add 2 cups of water to the potatoes.
Mix well and bring it to a boil. Then turn the heat to low.
Add the beaten yogurt to the pan in small spoonfuls while stirring the mixture, so the yogurt does not curdle.
Keep stirring continuously and bring the mixture to a boil. Then add in salt and mix well.
Sprinkle some kasuri methi (dry fenugreek leaves) on the top.
Add chopped coriander leaves to the curry and mix well.
Dahi Aloo are ready. Serve them hot with any Indian bread like paratha, puri or roti.