Cook quinoa to package directions with the 1/2 tsp salt. Transfer cooked quinoa to a large bowl, fluff with a fork and let cool to room temperature.
Dressing: Whisk lemon juice and garlic powder in a small bowl. Gradually whisk in olive oil.
Toss the cooled quinoa with the dressing veggies, chickpeas, feta, mint and parsley. Season to taste with salt and pepper. Serve at room temperature or chilled.