Boil the potatoes in their jackets and allow them to cook completely. Day-old potatoes that have been refrigerated work very well for this dish. Peel the potatoes and cut them into 3/4 inch dice. I actually used mini red potatoes, and left their skins on.
Break up the cauliflower into chunky florets that are about 1.5 inches across at the head and about 1.5 inches long. Soak the florets in a bowl of water for 30 minutes. Drain.
Put the oil in a large, perferably nonstick, frying pan and set over medium heat. When hot, put in the cumin seeds. Let the seeds sizzle for 3-4 seconds. Now put in the cauliflower and stir it for 2 minutes. Let the cauliflower brown in spots. Cover, turn heat to low, and simmer for about 4-6 minutes or until the cauliflower is almost done but still has a hint of crispness left. Put in the diced potatoes, ground cumin, coriander, turmeric, cayenne, green chili, ground roasted cumin seeds, salt, and some black pepper. Stir gently to mix. Continue to cook uncovered on low heat for another 3 minutes or until the potatoes are heated through.