Preheat your oven to 425°F (220°C).
In a large bowl, toss the chopped cauliflower and potatoes with the oil and all the spices.
Spread everything out on a large sheet pan in a single layer — no overcrowding.
Roast for 35 minutes, flipping once halfway through, until the veggies are tender and golden at the edges.
Sprinkle with fresh cilantro and a squeeze of lemon just before serving.