Peel and dice the potatoes into medium-sized cubes. Finely chop onions and tomatoes. Slit the green chilies lengthwise. Keep all ingredients ready.

Heat oil in a pan over medium heat. Add mustard seeds and let them splutter. Then, add cumin seeds and sauté until aromatic.

Add slit green chilies and ginger-garlic paste to the pan. Sauté for a minute until the raw smell disappears.

Add finely chopped onions to the pan and cook until they turn translucent.

Now, add turmeric powder, red chili powder, coriander powder, and salt to taste. Mix well and cook for a couple of minutes until the spices are well combined.

Add the diced potatoes to the pan and mix them gently with the spice mixture until evenly coated.

Cover the pan and let the potatoes cook on low heat until they are tender, stirring occasionally to prevent sticking.

Once the potatoes are cooked through, garnish the sabji with freshly chopped coriander leaves. Serve hot with roti or rice.