Preheat the oven to 400 degrees Fahrenheit.
Pound the cumin seeds and carom seeds in a mortar and pestle until coarsely powdered.
Place the powdered seeds and all other ingredients except the potatoes in a bowl. Mix well and drizzle in the water, using a small wire whisk to ensure there are no lumps.
Toss the potatoes in this mixture, ensuring each potato gets coated.
Line a baking sheet with parchment paper and spritz the surface with a cooking spray. Place the potatoes on the baking sheet, ensuring they are spread evenly and do not overlap.
Spritz once more with the cooking spray and place in the hot oven. Roast for 45 minutes, turning over once halfway through roasting with a spatula, or until the potatoes are golden and cooked.
Garnish with some cilantro, if you wish, and serve hot as a snack or a side.