01 - Preheat the oven to 425°F. Position rack in the center of the oven.
02 - Combine carrots and red onion in a large bowl. Drizzle with olive oil, then sprinkle with cumin, smoked paprika, salt, and pepper. Toss until evenly coated.
03 - Spread seasoned vegetables in a single layer on a rimmed baking sheet. Roast for 25 to 30 minutes, stirring halfway through, until carrots are tender and edges are caramelized.
04 - While vegetables roast, combine quinoa and water (or broth) in a medium saucepan. Bring to a boil over high heat. Reduce heat to low, cover, and simmer for 15 minutes until liquid is absorbed. Remove from heat and let stand covered for 5 minutes. Fluff with a fork.
05 - Whisk together Greek yogurt, chopped mint, lemon juice, salt, and pepper in a small bowl until smooth. Refrigerate until ready to serve.
06 - Divide cooked quinoa evenly among four serving bowls. Arrange roasted carrots and onions on top along with baby spinach. Sprinkle with chopped pistachios.
07 - Drizzle mint yogurt generously over each bowl. Garnish with additional fresh mint leaves if desired. Serve immediately while vegetables are still warm, or enjoy at room temperature.