Place quinoa in sieve and rinse in cold water.
Combine quinoa and 2 cups water in medium saucepan. Bring to boil over medium-high heat. Reduce heat to low, cover and cook until quinoa is fluffy and water has been absorbed, about 15 minutes.
Chop carrot and pistachios. Slice cherry tomatoes in half and lemon into wedges. Peel and section orange. Set all to side.
Fluff quinoa with a fork and place into large bowl. Add chopped carrot, cherry tomato halves, orange sections, and chopped pistachios. Toss to combine.
In a small bowl combine Greek yogurt, tahini, and lemon juice. Season with salt and pepper to taste. Whisk until well combined. Drizzle over quinoa salad.
Serve. Decorate with rosemary sprigs on top and lemon wedges (optional).