Boil the potatoes in salted water until tender, but not mushy. Do not peel. Let cool. Once cool, chop into bite sized pieces and set aside.
Heat the oil in a large nonstick pan or wok over medium high heat. Add the cumin seeds and minced chile pepper--they should sizzle. Let them cook for 30-60 seconds, stirring. Add the potatoes with a pinch of salt to taste (remember the chaat masala has salt) and toss. Cook for 1 minute.
Add the ground coriander, cumin, fenugreek and turmeric. Toss. Add the cabbage, spinach, cilantro with another pinch of salt. Toss. Cook, tossing occasionally, for 4 minutes. Toss in the tomatoes and heat briefly before transferring to a serving dish. Sprinkle chaat masala over the top of the dish, toss once more in the serving dish, and sprinkle again with chaat masala.
We enjoyed this dish leftover, but this particular dish is best the night it is made because the cabbage is still crunchy.