Boil 2 cups of water with 1/2 tsp salt and a pinch of turmeric powder. Turn off the heat. Put the cauliflower florets in to the boiling water. Close the pan and leave it for 3 minutes. Then drain the water and wash the cauliflower thoroughly.
Heat oil in a pan add mustard seeds. When it pops add the urad dhal and fry until golden. Add ginger, garlic and fry for few minutes. Then add the chopped onions and fry until it is translucent. Add the chopped tomatoes and mix well. Then add the boiled potatoes and the cauliflower and fry for few minutes. Add red chili powder, turmeric powder and salt. Mix well and sprinkle very little water. Lower the heat and cook for few more minutes. Garnish with chopped cilantro leaves.