Preparation Preheat oven to 450°F. Bring quinoa and 4 cups lightly salted water to a boil in a medium saucepan. Cover, reduce heat, and simmer until quinoa is tender, 10-15 minutes. Add onion; cook for 1 minute longer. Drain; return quinoa mixture to saucepan, cover, and let sit for 15 minutes. Fluff with a fork and transfer to a large bowl; let cool. Meanwhile, lightly coat a large rimmed baking sheet with oil. Whisk cider and honey in a large bowl to blend; season with salt and pepper. Add carrots and toss to coat. Transfer to prepared baking sheet and roast until tender, 15-20 minutes. Let cool. Whisk vinegar, lemon zest, and lemon juice in a small bowl. Gradually add 1/4 cup oil, whisking until dressing is blended. Season vinaigrette with salt and pepper. DO AHEAD: Quinoa, carrots, and vinaigrette can be made 6 hours ahead. Cover and chill separately. Add beets, dill, carrots, and half of vinaigrette to quinoa mixture and toss to coat. Add lettuce and remaining vinaigrette and toss to combine.
Preparation Preheat oven to 450°F. Bring quinoa and 4 cups lightly salted water to a boil in a medium saucepan. Cover, reduce heat, and simmer until quinoa is tender, 10-15 minutes. Add onion; cook for 1 minute longer. Drain; return quinoa mixture to saucepan, cover, and let sit for 15 minutes. Fluff with a fork and transfer to a large bowl; let cool. Meanwhile, lightly coat a large rimmed baking sheet with oil. Whisk cider and honey in a large bowl to blend; season with salt and pepper. Add carrots and toss to coat. Transfer to prepared baking sheet and roast until tender, 15-20 minutes. Let cool. Whisk vinegar, lemon zest, and lemon juice in a small bowl. Gradually add 1/4 cup oil, whisking until dressing is blended. Season vinaigrette with salt and pepper. DO AHEAD: Quinoa, carrots, and vinaigrette can be made 6 hours ahead. Cover and chill separately. Add beets, dill, carrots, and half of vinaigrette to quinoa mixture and toss to coat. Add lettuce and remaining vinaigrette and toss to combine.