Preheat the oven to 450°.
Scrub the carrots to remove any dirt and trim the green parts. Depending on the size of the carrots, cut the large ones in half so that they're roughly the same diameter as the smaller carrots, for more even cooking times (I had lots of different sized ones). Trim the root and stem from the onions, peel and slice into wedges. Transfer carrots and onions to a large, rimmed baking sheet.
In a small bowl combine the paprika, cumin, cayenne, cinnamon, salt, pepper and sugar. Drizzle the olive oil over the vegetables and toss with your hands until they are well coated. Sprinkle the spice mixture over the vegetables and toss again so that they are evenly coated. Spread the vegetables out on the baking sheet in a single layer.
Bake the vegetables for 20 minutes or until tender. Remove from the oven and transfer to a serving platter. Sprinkle with the pistachios, mint and cilantro. Serve with lemon wedges to squeeze on the vegetables for a bright hit of citrus.