Peel the potatoes and cut them into cubes. Boil 1 cup of water in a pan and add potato cubes and cook for 8 minutes on high flame. After 8 minutes strain potato and keep them aside. (Do not overcook the potatoes)
In a grinder add tomato, green chilli, and make a smooth paste.
Now heat 2 tbsp ghee or oil in a kadai. When the oil is hot, add cumin, turmeric powder, coriander powder, sabzi masala, ginger and saute for a minute on low flame.