Preheat oven to 425 degrees F. Line a 15x10x1-inch baking pan with foil; set aside. In a large bowl stir together oil, sugar, mustard seeds, ginger, turmeric, cumin, coriander, salt, and crushed red pepper. Halve any large carrots lengthwise. Add carrots and cauliflower to spice mixture; toss to coat.
Transfer vegetables to the prepared baking pan. Roast about 30 minutes or until vegetables are tender and starting to brown on the edges, stirring twice.
Transfer roasted vegetables to a serving dish. Sprinkle with cilantro. Serve with lime wedges to squeeze over vegetables.