Peel and slice the potatoes. Set aside.
Heat oil in a pan over medium heat. Add chopped onions and sauté until they become translucent, for about 2 minutes.
Add cumin seeds and nigella seeds, continue to sauté for another minute.
Stir in the ginger-garlic paste and cook for a couple of minutes until the raw smell disappears.
Add the tomato paste to the pan and mix well. Cook until the oil starts to separate from the masala.
Next add the spices. Stir to combine and let it cook until the spices are well-mixed and oil surfaces.
Add the sliced potatoes to the masala mixture. Cook for 5-6 minutes, stirring occasionally, until the potatoes are slightly seared.
Pour in the yogurt and mix it well with the potato masala. Cook for another 2-3 minutes.
Add water as needed to achieve your desired consistency for the curry. Cover the pan and let it simmer until the potatoes are softened, stirring occasionally.
Once the potatoes are cooked, garnish the curry with sliced green chilies and chopped cilantro.
Serve the spiced potato curry hot with rice or bread (roti/paratha) of your choice.
